I like his videos, but I don't trust his numbers in this one. He shows a COP of ~1 when it's 10 degrees out. These are the easiest possible conditions for the HP, and where all the specs show the highest COP. His graph showing the HP is running equal to a baseboard heater seems very suspect.
The issue with the COP graph (9:05) is that it's comparing the mini-split system to the prior system. The mini-split doesn't have radiators in the same place as the prior system, so he runs it 1-2˚ hotter (7:50) to get the rest of the house to the same temperature. Also, the system isn't using much electricity on warm days (8:48), so the inefficient placement of the minisplit is more dramatic.
The more interesting graph is the total kWh saved per day (8:07). The colder it gets, the more energy he saves. That's because more heat needs to be pumped into the house, so a worse COP multiplied by more total heat equals more electricity savings (at least for the temperatures he's measured).
He's located in NB, so I assumed it was Celsius. To check I just compared them to the Environment Canada data it seems to match pretty close for NB in Celsius.
Can't recommend this channel enough, it's like the Captain Disillusion of home appliances. The video about hurricane lamps was the first I saw, and it solved questions I didn't know I had about their weird shapes.
He does, but he omits a lot of important considerations that make heat pumps impractical for normal Americans.
If he touches on them, it's briefly - if at all, e.g.:
- More expensive units, and more expensive to run power wise. It's always difficult to get adoption of new technology that's "better" but more expensive to buy & repair - to the point where RoI may never happen.
- Power grid implications during very low/record low temps e.g. shortages/blackouts, likely worse than those in summer if heat pump uptake is widespread.
- With a heat pump, you -need- an alternative source of heat - since some days when it's particularly cold, they just won't work, or work very inefficiently. Plus, if the power goes out... you're definitely not powering a whole house heat pump with a small generator like you could a natural gas furnace.
Edit: FWIW, I'd researched this topic heavily & seriously considered getting a heat pump to pair with a solar power setup. For a number of reasons (chief among them: no return on investment before the end of the heat pump's expected service life), I will not be getting a heat pump any time soon. That may change if prices drop dramatically, but that seems unlikely given their increased mechanical/electrical complexity.
Just to soften a few of your confident declarations.
> normal Americans
Please revise this phrase. America consists of many different climates and it's very unclear what you mean or why you chose the word "normal."
> More expensive to run power wise
You're comparing new gas HVAC vs new heat pump. However, don't forget about all the folks that are purchasing a heat pump to replace an existing gas unit! For example, my gas unit (Goodman unit used in California) is old and not even energy star compliant! A new heat pump will be more efficient.
> With a heat pump, you -need- an alternative source of heat
By 'you' are you referring to me (or, say, the ~7% of the US population that lives in my small area of the country)? If so, that's not true! It doesn't get too cold here. And I reckon there are quite a few areas in this country where it doesn't get cold enough for a heat pump to eat shit.
When you refer to prices and returns on investment, are you using a unit + professional installation cost (like $18k+ or something)? Or the unit itself (~$4.5k) plus perhaps a DIY installation costs (~$1.5-2k)? There is a big range there in costs, and the ROI is dependent on that.
I put in a new Mitsubishi Hyper-Heat heat pump last summer. It got down to 17 Farenheit in Seattle this winter. There are no heat strips or supplementary heating arrangements. The heat pump performed well the entire winter.
My energy bills are 1/2 of what I was paying with an electric furnace last year.
I too live in Seattle and have friends who bought a heat pump; they ended up in a hotel room and until they could had a HVAC company come to their home and install a backup heat source.
In Seattle are highest usage months for electrical is in the winter, right when you will be maxing out that 50A breaker you had to install in order power that beast; check the notes from Mitsubishi, they are clear that it is not an efficient device in the range you suggest ( and seeing how in Seattle most homes are still at 100A service you must either be living in a newer home or one with an upgraded service ).
You realize that Seattle is now an importer of electricity and is no longer running surplus?
Or how about that the city has been using an unsustainable amount of water? ( i.e. where our power comes from ) Or that our electrical come at the expense of Salmon and the endangered Orca pod that lives in the Sound?
If you replaced your "furnace", which implies a central HVAC system, with a Mitsubishi Hyper-Heat, which I believe is only installed as a mini-split, what are you doing about your air quality?
The Seattle area suffers from "inversions" through out the year; a mini-split does nothing for air quality issues. The smoke that we dealt with in the fall? That wasn't even the worst air quality issue we have had in the last decade.
I am sure your electrical bills are 1/2 of what you were paying for an electric furnace, but unless you are abandoning the use of your heat pump for providing cooling your overall energy yearly costs are unlikely to go down.
I don't know situation, I don't know what options you had when you installed your unit, and I have not listed all of the good and bad that come with the unit that you installed.
There has been a lot of "mini-splits will save the environments" coming out of our City Council; there have been zero reports presented that back up those statements. The local heating and cooling people are happy to install units which have a higher markup/generate more work for them.
- Better than resistive electric heating for the grid. Gas is going away so this is a problem that has to be solved anyway.
- Economies or scale will solve the repair and maintenance burden... hell, it's not like a gas boiler is maintenance free...fucking things requiring serving every year and break down all the time in the UK.
- almost noone has a generator when the power goes out anyway. This is a very wealthy American perspective.
- Sure, at least when it's not super cold. Electrical grid may be a "problem that has to be solved" but it's one that carries staggering price tags and will have to be gradually transitioned into over decades. Natural gas will likely still be used as a heat source for many well into the late this century if not longer.
- Gas boilers are far simpler units. Less moving parts, simpler electronics, all in all fewer points of failure than a cutting edge heat pump that can actually produce heat when it's below 20f (-7c, i.e. the only kind of heatpump that might stand a chance at heating throughout the cold winters most of the northern US gets).
- Be that as it may, heat pumps at this time are cost prohibitive - making them largely something only "wealthy Americans" can afford. Many people still run old 80% efficiency units because of similar reasons to boilers: they're cheaper, simpler, and less likely to fail.
>> all in all fewer points of failure than a cutting edge heat pump that can actually produce heat when it's below 20f (-7c, i.e. the only kind of heatpump that might stand a chance at heating throughout the cold winters most of the northern US gets).
My family has one in Poland, it was -20C this winter already and it worked absolutely fine. It's some cheap unit, wouldn't call it "cutting edge". I think there's a simple resistive heater that de-ices the fins at low temps, but it kept the interior of the house at a (very toasty) 24C pretty much non stop even in those low temperatures. I have no idea why people keep saying heat pumps don't work in low temps. I had a basic split unit fitted to my home in UK, literally a basic £600 midea unit and apparently it should work down to -25C without any problem.
>>Gas boilers are far simpler units. Less moving parts, simpler electronics
Have you ever looked inside a modern gas boiler??? I hard disagree that it has less parts than a modern heat pump. A heat pump is like your fridge - there's an inverter, compressor, and a whole bunch of fins, that's about it. A gas boiler has multiple tanks, burn chamber, exhaust recirculation, at least 5-6 probes to measure every part of the process(and they all can fail in surprising ways that renders your boiler dead).
A solution doesn't work in 100% of areas can still be the best one in the 95% of the places that do make sense!
And to your cost concerns, there's a bunch of Federal money (being deployed by the states) in the IRA to specifically pay for low-income Heat Pump upgrades.
88% of US households already have heat pumps, and 66% of households have centralised heat pump systems - otherwise known as air conditioning.
If you can afford to have them just for cooling, you can afford to have them for heating as well; in fact, the capital cost may well be lower if people just used their air conditioning systems to heat as well.
The same goes for reliability - we manage to make air conditioning acceptably reliable and the tech is basically the same.
I've lived all around the US, and don't think I've ever lived anywhere with central air. Well, that's not quite true: in New Mexico I had a roof mounted swamp cooler, but that's evaporative cooling and not a heat pump. Elsewhere I've occasionally had and used a portable compressor unit, but rarely. I hadn't realized air conditioning was so overwhelmingly prevalent. Based on people I know and associate with, I would have guessed less than half that rate.
I didn't quite grasp there was anything other than central air until recently in life (approaching 40). It's been the same everywhere I've traveled and lived across the US. I recall my grandmother's house having a gas floor furnace, which came in handy once during a blizzard.
I was surprised when a colleague from Minnesota who moved to the south mentioned never having air conditioning. I'd expect that in many parts of Europe. And I've sweated it out while living there, but it's extremely rare in my experience in the United States.
I've always had central air, along with a gas fireplace for emergency heat which, thankfully, I've never had to use.
> Be that as it may, heat pumps at this time are cost prohibitive.
They range from sub-$1K single zone air-to-air wall/window units, to multizone split units, to ground source hydronic boiler/chillers that integrate with baseboard or radiant floors, which can get quite expensive to install, but that's at the high end. Generally speaking they're not really much more expensive than normal air conditioning. I've seen units that come in cooling-only and heating+cooling versions, and the cost difference is marginal (<10%) in those cases.
Funny you think it's a wealthy American perspective to have a generator for outages. My thoughts went in directions of wealthy people in Bangladesh or India.
> He does, but he omits a lot of important considerations that make heat pumps impractical for normal Americans.
Some form of this comment always comes up in these heat pump threads, and I never understand the idea that heat pumps are some elite affectation that doesn't make sense for anyone else. Many millions of Americans live in parts of country where it gets warm enough in the summer to justify central air conditioning and chilly enough in the winter that you need heat but the heating source doesn't need to handle super low temps on a regular basis.
A heat pump is literally one of the simplest ways to address the year round climate control needs for those people since it's a single system that handles both heating and cooling with only marginally more complexity than the air conditioner you'd want anyways. Throw in electric backup heat, which is probably the simplest backup and keeps the system all-electric, and you have a system able to handle a pretty broad range of temperatures all year. As heat pump technology gets better, the applicable temperature range gets colder and colder and makes heat pumps practical for a wider range of "normal Americans".
This isn't just theoretical. Heat pumps account for 17% of heating systems in the US, which isn't huge, but over 40% in North Carolina, South Carolina, and Alabama and a significant percentage in many other states as well. Obviously there are cases where heat pumps are at least currently impractical given the construction, climate, etc, but dismissing them as some effete toy seems a bit silly.
Edit: Interestingly, most states seem to have a significantly higher percentage of homes with electricity as their primary heating fuel than they do homes with heat pumps, suggesting a lot of homes with things like electric baseboard heating. While not all of those homes necessarily have central AC, using Georgia as an example, 85% of homes have central AC and 53% use electricity as their main heating fuel, while only 29% have heat pumps. That suggests quite a few homes with central AC that use electric baseboard or similar. Heat pumps for those homes seem like they'd be very practical.
>Modern heat pumps redirect some heat to prevent the coils from freezing. What you wrote is common FUD pushed by the oil & gas companies.
It's not FUD, and you COMPLETELY ignored & omitted the rest of my sentence from your quote. I'm well versed on how heat pumps work. I was not saying heat pumps don't work below freezing. Rather than simply repeat myself, let me rephrase:
1. Heat pump efficiency gets worse the closer you are to the minimum (outside) temperature they're rated down to.
2. Even with the best (and most expensive) technology, that means efficiency of these units approaches that of a $15 space heater.
3. When it gets TOO cold, they can stop working entirely if they don't have a resistive backup heat system (which, again, is effectively a $15 space heater you paid a lot more for).
Both Canada & the northern US experience these temperatures occasionally (-10f to -30f and worse on some occasions).
Hence the need for backup heat - e.g., a pellet or wood-burning stove, backup furnace running propane or natural gas, or even just something cheap and simple like a $150 portable diesel heater. You don't want to be left without heat in a multi-day power outage after a half inch of ice and high winds.
For backup heat, it's more efficient to burn whatever fuel for heat than run a generator outside to power space heaters or a heat pump at those brutally low temps that often follow those hard ice storms.
"Redirect some heat" from where? In the installs I've seen they did it from inside the house i.e. literally cooled the house down. The alternative heat is needed to keep the inside temperature up and work against the pump cooling your house down when it's already cold. Do you have some other alternative source of heat on the modern heat pumps?
Your whole argument is. Heat pumps need a secondary heat source because at the temperatures around 0C they accumulate ice on the heat exchanger outside. To melt the ice they reverse the energy flow so they cool the house and heat that heat exchanger. You asserted that it's just FUD and they can "redirect some heat" instead. This implies they don't cool inside and instead redirect heat from elsewhere (second outside heat exchanger perhaps?).
But it appears there is no second heat exchanger outside and the modern heat pumps work just like heat pumps from couple years ago.
As for keeping the functionality - it's a philosophical question. For me personally, if I turned on the heater because it's cold inside and it started blasting cold air, I'd call the repair people immediately. While it still works in the sense that it makes noise and consumes energy, it stopped performing its function of heating so I'd consider it lost the functionality I am interested in the most.
> With a heat pump, you -need- an alternative source of heat
It's only a -need- in certain locations. The one I have claims to be fine down to -5 degrees. There is zero chance we will get anywhere close to that in my lifetime. Heck, even getting down to 32 is incredibly rare. So we are fine without an alternative source of heat.
As for other points, we have never had a power loss/blackout in the nearly 3 decades we have lived here. And electric is cheaper than gas due to nearby hydroelectric dams.
The alternative heat point is interesting, you don't need to be able to heat your entire house with alternative heat for extended periods of time. If properly designed, 99% of the hours of the year should be warm enough for the heat pump to provide 100% to heat and the remaining hours can be made up with a small space heater or a fire or something else minimal.
Seems like OP just performed a stress test on his website as he is the "Webmaster of https://hvac-learning.com an HVAC elearning website"[1]. Hopefully you can figure out something! Thank you for educating about such technology!
I am sorry for the inconvenience. I am still learning how to build a nice and efficient website. I will analyze what happened and try to fix and enhance !
I love that you're building free educational resources, especially about something like this! If you need help/advice to help build your website, email me (see my profile), I'll be delighted to help pro bono. :)
Oh I have a question for the community here about heat pumps. I have three mini splits that I use for AC but connecting them to a home hub is bananas amount of work and inconsistent (Mitsubishi brand). I wish there was a legitimately good, robust system to connect AC units to my smart thermostat (Ecobee) or even some of the other devices I have.
It still feels the wild west for home energy systems - and the costs are quite high for the value they provide.
So far I've been happy with using the mysa ecosystem for my smart home. It works with Apple HomeKit, its had relatively good reliability and the team behind the product have been responsive when I do face issues.
What is going on? Is there a global push to get everyone to switch to heat pumps. It seems that there is heat pump content everywhere. Clearly there is a push.
I understand that its for climate benefits but it feels very coordinated.
edit: didn't realize the attention I would get. Let me add someone answered my question -- a good product market fit and people talking is probably where the push came from. That said HVAC installers / heat pump manufacturers and governments are all pushing this hard right now. I believe in the benefit for most people and the climate benefits are great. I am always concerned on when there is large consensus on a hard push - worth looking at who the winners are and what the trade offs are.
For a long time the main problem of heat pumps was that while they are more efficient, a kilowatthour of gas or oil is much cheaper than a kilowatthour of electricity. But in the last two years natural gas prizes have gone crazy, removing that price disadvantage.
Of course heat pumps emitting no particulates and being able to run on renewables are also good reasons, especially as the health impact of living in cities with high PM2.5 values becomes clearer. But I don't think those are the primary drivers.
Heat pump technology has also improved significantly. You can now buy heat pumps that remain efficient down to very low temperatures, which makes them appropriate for a larger range of climates now.
Many models are in very high demand. Some of the units I looked at recently were back ordered so far that I was told to pick something else if I expected to have it within the year.
The demand is very high because the technology is good. It’s not a campaign or conspiracy.
The war in Ukraine has resulted in a real push to get off of oil/gas based heating, on top of global warming concerns that have already been doing that.
There are lots of different groups looking to push heat pumps for the above reasons. Governments are concerned about both war and global warming. Ukraine supporters are concerned about Russia getting more money (to wage more war). Green activists are concerned about global warming. All have their own reasons to push heat pumps on everyone.
It's not directly related to the recent spike in prices, especially considering that a heat pump installation is very expensive in itself and potentially disruptive.
Rather, it's a combination wanting to get to net zero, so no emissions, with the big problem of generating enough green electricity. A heat pump system has no emissions and consumes much less electricity than an electric boiler/electric heater.
They are also kind of a 2 in 1 appliance, in that they can run in reverse and cool your home, and are much more efficient at that than traditional ACs.
In the US where AC is common, summer is generally peak electricity usage. I suspect this will become true in Europe as well with the heatwaves becoming a regular occurrence.
> they can run in reverse and cool your home, and are much more efficient at that than traditional ACs.
I'd love to see a source on that. There is very little technological difference between an air conditioner and a heat pump aside from refrigerant reversing valves that allow changing which end is the condenser and which the evaporator.
I think as a general statement it's true, however the causal reason for that is not because they're heat pumps, it's because of the market for heat pumps is different.
If you poll the current installed base for HVAC, I suspect you'd find that the (vast) majority of systems are minimum SEER rated (i.e., least efficient) systems, so SEER 13/14 (just became SEER 14 this year).
In comparison, if you're already paying the premium for the heat pump system, likely you also pay an additional premium for a higher SEER unit. Also, what I've seen when doing some online shopping that most heat pump systems marketed seem to be higher SEER. Likely, because the cost associated with additional heat pump stuff drives into a higher end market where you 'might as well' make them higher SEER as well (with inverter compressors, variable fan speeds, etc).
The bigger reason is the japanese market demands efficiency. Buyers compare running costs.
Thus Japan acting as a breeding ground for cheaper, replaceable, mini splits. The American manufacturers sold into the HVAC specialist market which was efficiency insensitive but cost sensitive. Thus a bi-partite market.
The only reason mini splits have not bankrupted the American manufacturers yet is many Americans still rely on expensive HVAC specialist to do installs. Thus mini splits extreme cost advantage is buried by expensive installs.
A heat pump is an air conditioner that can run in reverse. Put another way, an air conditioner is a marketing term for a specific kind of heat pump. Your correct that there is no inherit efficiency different. Perhaps what was meant is that they are much more efficient than traditional resistance heating?
I guess to clarify, where I've lived the most common type of AC is a window-mounted unit. IIRC those are generally less efficient than the heat pumps getting installed today, to the point where my family got paid by our utility to replace the window units with them.
I replaced my old air-to-air heat pump with a new one last year. Cost me in total around $3000-$4000. Might have been a bit more expensive if it was a completely new install depending on how it would be installed, but not too much more expensive. Might be more expensive in countries where you are using gas boilers as it sounds like your heating setup is much more complex than where I live.
Here in the UK, I think the cost of installing a new heat pump, bearing in mind that it's an installation from scratch, starts at about £10k ($12k as today's rate) to several tens of thousands. A ground source heat pump (which seem to be the ones pushed by the gov?) is probably £15k to £30k if you can install one at all. Replacing an existing gas boiler, which is what most people have, is probably around £2k or even less in simple cases. I had mine replaced 2 years ago with the new one installed on a different floor so a fair amount of plumbing was required, and it 'only' cost me £3k.
There are government subsidies but it's still much more expensive in the end. I think they are simply too expensive and impractical to install for most people.
FWIW, I just installed two heat pumps in a 3100sf house in the US northeast this summer. We already had ducted AC. The main unit was US$17K and the mini-split for the master bedroom was US$6K. There a US$10K state rebate, but we'll probably only get 70% of that because we've retained the old heating system as a backup and for water, so total cost is US$16K. These are cold-climate units, both rated down to -4°F but I haven't actually made them work below 20°F yet. Next year I'll probably set the aux cutover temperature to something lower and see how it goes. Year after that we'll probably install solar (plus wind if the technology for that has moved along far enough) and switch to all-electric everything.
BTW my town has an all-electric mandate for new construction already, and there's a lot of that. There's also a bylaw that takes effect in 2025/2026 banning gas-powered landscaping equipment.
I think prices have spiked. Two years ago I installed a new heat pump to replace an old failing 5-ton air conditioner (which was paired with a high efficiency natural gas furnace; I kept the furnace as backup instead of relying on electric strips). It was $6K altogether. Was just going to replace the A/C with a new one, but the differential was $1500 and so I figured why not.
OTOH, a few months ago my stepmother installed minisplits after getting quoted $22K to install a whole-home forced air heat pump (going from no forced air at all, so part of that cost was ducting, though it's a single story ranch house so not terribly difficult).
Somewhere between those two points, prices went insane.
What heat pump did you get? I wanted to get a heat pump, but I ultimately ended up just buying AC. I was told it was not possible to pair with an existing furnace because heat pump control systems were proprietary and incompatible with a standard furnace control.
Which I absolutely don't get. I just had a mini split unit installed at our house here in North East, paid £1500 total with installation, and damn that thing throws a lot of heat - I literally stopped using our gas boiler, it's more efficient(and cheaper!!!!) to use this unit for heating than to burn gas. It uses like 800W of power when running but produces ~4kW of heat.
I imagine the "proper" heat pump costs a lot because it has to integrate into your central heating - heat and pump water etc. But I also imagine for a lot of people in this country 2-3 mini splits like this one would be absolutely sufficient, wouldn't cost a fortune, and would save them money(plus they can be used for cooling when needed).
And my local utilities just got approved for massive rate increases locking in those higher prices. Of course, I probably wasn't paying the full costs this past year.
An overlooked benefit is that they actually improve comfort over a boiler in a dry climate, so if you live somewhere with low humidity they help keep the air less dry. They also give you heating and cooling.. for places that don’t have Air Conditioning it’s a worthwhile upgrade.
Sorry but this is incorrect. Boilers aka hydronic heat is usually delivered through baseboard fin-tube or hot water radiators. These heat mostly through convection with some radiation. Any humidity in the house is retained. Forced air heats the air and removes humidity absent a humidifier.
Forced air doesn't remove humidity from the air either. Humidity is lost through air leakage in homes. Since the air outside had less absolute humidity in the air then humidity will drop due to air leakage. Most measurements of humidity is relative humidity though which changes with air temperature. So any system that heats air will reduce relative humidity.
I assume in home that don't have ACs, that they also don't have ducts. Do these ductless homes filter their air, control home humidity, or bring in fresh air from outside?
My ductless house has a gas combi water heater/boiler and hot water circulation system to in-wall radiators with simple blower fans.
The house also has an exhaust fan on a timer, paired with small vents on several windows around the house, to cycle in fresh outside air. But practically for much of the year we just open the windows for fresh air since we live in the temperate PNW climate, wildfires aside :(
I looked in to installing a minisplit heat pump system last year, but the quotes I got were outrageous ($25k+) plus as a retrofit it's not the most elegant integration. Someday I'd like to do the conversion and ultimately decommission the gas boiler, but at that price tag it's not happening soon.
In the short term I bought one window AC and one portable AC for a combined ~$1000. It's not ideal but we only have a few weeks a year where cooling is really needed, and a few more where it's a nice luxury but not a necessity.
"Ductless homes" usually circulate hot water through radiators. If you switch to a heat pump, nothing's stopping you from circulating cold water in the summer, though obviously there is a limit on the temperature delta (you can heat water much more than you can cool it). Bringing in fresh air is a manual process (open the windows), and filtering air or controling humidity is then left to seperate appliances, if done at all. Though small fans to the outside for forced ventilation are gaining some popularity for giving you automatic air exchange and filtration.
There are many reasons why you can't just circulate cold water though a radiator to cool. As another commenter stated you will get large amounts of condensation. But the other reason is that you do not get nearly as effective of convection currents with cool versus heating. Your radiators utilize convection currents to circulate the warm air around the room. Running chilled water though the a radiator would be like having an ice cube in the corner of the room. It isn't going to cool the whole room down and will get water everywhere.
> nothing's stopping you from circulating cold water in the summer
Condensation is - air conditioners have an integrated drip tray which drains to the outside, but if you ran chilled water through radiators they'd all make puddles of condensation on the floor. Retrofitting drains might be possible but I've never seen one and I can't imagine it'd be cost-effective vs installing mini-splits.
Maybe a faulty assumption; my AC-less home has a ducted oil furnace, and we still haven't removed the ducts after installing a heat pump. Another house I lived in 12 years ago had ducts for oil furnace heating but no AC. Both were 100+ years old and in the northern US.
That matches my experience. All of our older houses around here with oil heat are forced air. Radiators are uncommon. But 'older' in this case is only 100-120 years.
My parents installed a whole home humidifier a couple of years ago. It cost way more than $300 (closer to $2k installed—maybe they just got the wrong one?), and it also costs a lot to operate each month in additional electricity usage. Having a system that doesn't require one sounds much nicer.
I got quotes in that range as well here in boulder, so I installed one myself a week ago in about 2 hours(aprilaire 700 - $310) with no special HVAC knowledge, though I am mechanically and electronically inclined.
I haven't checked the electricity usage but I can't imagine it is much. The system is literally just a small fan and a solenoid valve. Maybe your parents opted for a steam system, whereas mine is called a flow through style.
That's like cautioning about the price of cars because you bought a Hummer instead of a Corolla. Drum humidifiers use a couple watts on any central forced-air system.
And, since the heating season is there only time you need humidifying on this context, all the "waste" heat is just heating your home.
Well of course it is being pushed, though I would not necessarily call it coordinated.
Companies that sell heat pumps are advertising hard. It's an easy sell for them with rising gas prices.
The US government is "pushing them" by offering tax credits for heat pump systems. This is part of a plan to reduce pollution, improve energy independence/energy security, and save citizens money on their heating bills. No secret there - politicians and public servants are excited about this and they are talking about it. They are also offering tax credits for other high efficiency heating systems, but not that many people are looking at those tax credits because buying a new high efficiency gas furnace doesn't make that much sense when you could buy a more efficient heat pump instead.
Many individual people are also talking about them because they are a great way to help the environment and save money at the same time.
And I think a lot of people just think they are cool technology as well.
I think this is probably the right answer. It keeps popping up everywhere.
I'm always a skeptic on when something gets super hyped. In this case it's more use-case specific that makes me skeptical - majority of people its 100% fit.
I also tend to be skeptical when I see something hyped, but I work in this space and I can say that this tech is really the best option for most residential applications.
It's old tech, it's been around since the 1800s. The only thing that has changed is that heat pumps have gotten cheap and energy has gotten expensive.
There are applications where heat pumps cannot replace boilers - in industrial processes where high temperatures are required or tremendous capacity is needed intermittently.
However, unless your temperatures are routinely below about -20 F, a heat pump is the best choice (and even if temperatures occasionally drop below that, heat pumps are still an excellent choice because those extreme temperatures might only last for a handful of hours out of the year, during which insulation or a cheap electrical resistance heater can keep you warm).
I don't know if it applies everywhere, but two factor come to mind: the (somewhat recent) change in energy and gas price did make heat pump a lot more competitive with more traditional heating solutions, and recently there are a lot of economic incentives (at least, here in Europe) to renovate house for energy efficiency, which make solar panel and heat pump very attractive.
> and recently there are a lot of economic incentives (at least, here in Europe) to renovate house for energy efficiency, which make solar panel and heat pump very attractive.
Economic but also legal and geopolitical: fuel oil furnaces are getting restricted or banned, and the combination of climate change, air quality standards, and russian instability makes gas look at lot worse than it did 10 or 20 years back.
Yeah. If some people came together at Davos or whatever and decided "we need to promote heat pumps!", you can be sure they would mess it up. Consent can maybe be manufactured. Enthusiasm is organic, for good and bad.
Agreed that top-down programs aren't always very effective (although sometimes they can be), but would point out that "coordinated" doesn't imply top-down. It could just mean that lots of individual entities are working with each other to achieve a common goal.
They are not more energy efficient than burning gas.
Edit: since i am getting downvoted to oblivion, let me fight back here. I genuinely wished heat pumps would be more efficient and in theory they can be. I would love to not generate heat and just use the outside heat energy and compress it down into a smaller location.
But compressing and decompressing is not an energy efficient task. It takes a lot of work. Mechanical inefficiencies are a huge energy consumption. Gas is simply burning fuel. Yes, we should save gas for rainy days. But I hate to say that it is more efficient and cheap. There is no comparison.
They literally are more efficient than burning gas, a good heat pump can do over 300% efficiency (KWs of heat in your house vs KWs of electricity used) while a furnace can only hope to get 100%. Even if the heat pump is fed from gas power plants (which burn gas with about 50-60% efficiency, more if the waste heat is reused), they are still using less gas for the same amount of heat than directly burning it.
> (CCGT) plant[s] achieve a best-of-class [...] thermal efficiency of around 64% in base-load operation. In contrast, a single cycle steam power plant is limited to efficiencies from 35 to 42%
If that where there would be no discussion about the switch to heat pumps. But it isn't. In old houses (bad insulation, old radiators) and edge cases ("winter") heat pump are not just inefficient they may not be able to heat the house at all (unless extremely oversized).
This is a huge problem in Europe where a house is expected to last a 100 years, in many areas much more.
Slightly unrelated, I have a friend who moved to the US from Mexico and was asking me about potentially buying a house. He started looking on Zillow with me and his reaction to houses build in the 1950s OMG how can it be that houses are that old and my reaction was wow that's pretty much a brand new house. He was blown away that a huge percentage of houses on the market are from the early 1900s and even late 1800s where we live.
It's true that good insulation and sufficiently sized radiators are important. But it's not like those things can't be upgraded in existing houses. In fact, if we're talking about energy efficiency then insulating houses should likely be the first action taken.
Yes, because a heat pump is taking the heat from the outside environment and moving it into your house. You’re only paying the “transportation cost” and not the actual cost to generate heat. The heat was generated by the sun.
So the term efficiency with heat pumps typically refers to COP Coefficient of Performance. It a measure of how many watts of heat you are able to pump per given watt of electricity used. So 400% would be a COP of 4.0 which is definitely possible with air source heat pumps in milder weather and ground source heat pumps in pretty much any weather.
The core idea is that you aren’t using 1 unit of electrical energy to create 1 new unit of heat energy. You are using 1 unit of electrical energy to capture several units of pre-existing heat energy from the environment and pump it indoors.
Yes so not only are you capturing heat from the environment you are turning electricity into heat in the compressor, both are delivered as heat to the interior. This is an advantage compared to cooling where you must reject both the interior heat and the heat of compression.
To add to the other answer, if you calculate the absolute limit on performance for heating and cooling using the Carnot cycle, the 'heating' case is always going to be '1' higher than the cooling case, because you also get to use the 'work' heat.
If you measure the efficiency of heat output relative to the electrical input power, then yes. The trick is that there's actually another input: latent heat in the environment. But given that this is abundant and freely available we don't usually bother to include that in our calculations.
They can be, natural gas is about 1000 BTU per cubic foot.
An expensive high efficiency gas furnace might be 95% efficient (most normal furnaces are in the 80's)
1000 x 0.95 = 950 BTU/cuft
A high efficiency natural gas power plant is 60% efficient and a modern high efficiency low temp heat pump can have a COP up to around 2.7 at 17F
1000 x 0.6 x 2.7 = 1620 BTU/cuft
A 40% power pant is still more efficient than a 95% furnace with a 2.7 COP heat pump.
There is obviously more to this, there are some grid losses to account for but has to be compared to piping losses, there is also cost factors and also how much renewable is mixed into your grid supply, but generally once that heat pump is above around 2.5 COP it starts to make sense, this is a no brainer in milder climates which is why I have a heat pump and no gas furnace here in FL even though I have gas to the house for other uses.
> this is a no brainer in milder climates which is why I have a heat pump and no gas furnace here in FL even though I have gas to the house for other uses.
They're a no-brainer in every climate. Newer heat pumps can handle fairly cold temperatures (-13°F) pretty easily, there may be a loss in efficiency but in the majority of the world it doesn't stay that cold. A few days of lower than normal efficiency, and at worst plugging in a few space heaters if it gets extremely cold for a day or two, does not change the overall math of heat pumps being a better solution.
Hell, that's just me talking about air source heat pumps. No reason for new construction to not use ground source and get better efficiency and not worry about ambient outdoor temperatures.
So heat pumps do lose efficiency at lower temperature such as -13F but the much bigger issues is loss of capacity. If you look at the curve of available heating capacity of a heat pump versus the heating needs for your house that tend to be a bit of a mirror image. When it is warmer out your house needs less heat but heat pumps have the highest capacity they will have. As temps drop the house will require more heat while the capacity of the heat pump is dropping.
That isn't to say they cannot work I personally have a heat pump in my house and it worked fine through the -15F weather we got. But it requires careful design work initially. Also you run into simply size constraints where residential heat pumps tend to max out at 5 tons (60k BTUs) typically when furnaces can easily get up into the 100k+ BTUs. Which might require multiple heat pumps and separating existing duct work. But definitely new construction should start designing around these constraints now.
> Which might require multiple heat pumps and separating existing duct work. But definitely new construction should start designing around these constraints now.
Ductless mini-splits remain an option as well. I'd actually like to see somebody make some ground-source exchanger that ductless heads could connect to, because they're much cheaper to install than a multi-zone ducted system.
They make systems like that but they tend to be more commercial systems. You could get a ground to water heat pump then run chilled/heated water to the mini split heads depending on what they are calling for but even that is pushing into commercial territory. And sadly with commercial HVAC comes significantly higher prices.
Ok! I am genuinely interested in how heat pumps are more efficient. My online search led me to calling heat pumps more efficient when compared to electric heaters. And better in other ways compared to gas burners. But lord's sake, they were all upselling marketing sites for heat pumps.
I am looking for genuine research, and not from paid mouth pieces.
Majority of the comments here seem like agents of heat pump industry. And HN rules forbid me from calling them that.
Physics. When combusting fuel you cannot get more heat energy out of them than the chemical bonds you are breaking contains, a gas furnace can never be more than 100% efficient, the best commercially available ones are 95%, and a majority that are actually installed are closer to 80-90%.
Heat pumps do not create heat, the refrigeration cycle moves heat from point A to point B. For every KWh of electricity used by your refrigerator, air conditioner, or heat pump, 3-4 KWh of heat energy can be moved where you want it to go.
Even if you have a (comparatively) inefficient combined cycle natural gas power plant that is 50-60% efficient, you're still getting 150-200% efficiency for heating with a heat pump compared to 80-95% for a natural gas furnace.
I live in Boise so we have pretty cheap utilities compared to the national average, but here's some math:
1 therm (~30KWh of energy) is ~$0.72 from Intermountain Gas, the furnace in my rental is 90% efficient, so I actually get 27KWh of heat from every therm I burn.
Idaho power has a tiered tariff for residential customers, with a peak charge of ~$0.098 per KWh during the winter for usage over 2,000 KWh in a month.
Every therm my gas furnace burns costs me as much as ~7.5KWh from the electric utility, but those 7.5KWh can provide me with 30KWh of heat with a quality heat pump, which would require a 100% efficient natural gas furnace to reach. Add in that gas furnaces have a much higher TCO because of maintenance and repair compared to a heat pump, and they're not just energy inefficient in comparison but even just plain more expensive to operate even with incredibly cheap fossil fuels.
Just do the math, all you need to know is furnace efficiency and COP of the heat pump along with the efficiency of your local power plant. I did that in my post, its not super complicated.
Gas is burned creating a certain amount of heat, in a furnace some is lost to exhaust the rest goes into your house. That is the furnace efficiency.
When gas is burned at a power plant the same number of BTU is released, but it is used instead in a heat engine to create mechanical power which is then turned into electrical power, the rest is lost to exhaust, this is the power plant efficiency.
Heat pumps are over 100% efficient because they capture heat from the environment around your house which is warmed by the sun. So even though more energy is lost in creating electricity than burning directly in your house, this is more than made up for by using the ambient heat around your house, it is essentially solar assisted (in the case of air source).
Did you watch the video linked on the highest rated post on this thread? The one from technology connections? It explains it all very well.
I am happy you have an open mind, but the fact that you are trying to tear the technology down when you apparently have no idea how it works or what it even is- hopefully you realize that it is also used for air conditioning, and is essentially just an air conditioner running in reverse... I hope this is a learning experience for you.
At the very least it gives me hope that those trying to tear down this technology are just ignorant, I had real suspicions that they were agents of the fossil fuel industry, or this was something Fox News and the like decided to target and is now being parroted.
I am in NY. And I think for Florida, a heat pump makes because of a hybrid AC model. Even if electricity is more expensive, the equipment and energy cost of a separate unit is not worth spending.
In extreme climates, gas burning is cheaper. And quite clean. There are some objections because of delivery leaks, but that is a separate concern.
As pointed out by several other comments, you're very off base about heat pump efficiency and about natural gas being "clean."
Switching everyone to heat pumps would lower emissions from heating and cooling in the US by 160m tonnes a year [1], which is something like 30-40%.
It's true that upfront costs of heat pumps can be higher, but thanks to the IRA there are huge subsidies available (and further subsidies in many states) which make up most or even all of that difference. The lifetime costs of heat pumps with these subsidies should be substantially lower than high efficiency natural gas furnaces.
Yes they are. You get more heating from an heat pump running from electricity coming from gas plants than what you get by just burning the gas. Including losses on the grid.
I cannot imagine this in anyway. Heat pumps work like ACs do. They do compress a medium till it heats up, and then spread that heat around. And then they decompress until it cools down and dump that cold until outside heat brings up the temperature again.
Those compressions and decompressions take up immense amounts of energy. They are less efficient than simply burning gas. On the flip side, could we not create electricity generation and heating from Natural gas?
I think you are misunderstand where most of that energy comes from. Say I have some refrigerant in liquid form at a low pressure. That refrigerant will have a boiling point of say, -20 degrees F. I use the ambient air, which is say 0 degrees F, to boil the refrigerant into a gas. The internal energy of the refrigerant goes up significantly, but it's temperature does not change. Then, I compress the gas so that it goes up in temperature. This change in temperature does not correspond to a large change in the internal energy of the gas. The same energy is pushed closer together, resulting in a higher temperature[1]. Then, I condense the gas at it's new boiling point, say 100 F, into a liquid. Then you decompress the resulting liquid and the cycle repeats.
Most of the energy is coming from the ambient air, only a small amount of electricity is used to change what temperature that energy is available at.
[1] A very simple mental model you can use to understand the difference between temperature and energy for a gas is that temperature is the number of times the gas molecules bump into each other in a second, while energy is how fast the gas molecules are moving. So if you have a very low pressure gas, even all of those molecules have a ton of energy in the form of motion, the temperature of the gas will be quite low because the gas molecules won't interact often. But compress that gas down to a small volume, and the molecules will bump into each other all the time even though they don't have much more energy.
That's the whole point. For most modern systems you get >4x of the energy in heat exchange compared to the energy you put in. You don't produce heat, you exchange it.
>But compressing and decompressing is not an energy efficient task. It takes a lot of work. Mechanical inefficiencies are a huge energy consumption. Gas is simply burning fuel. Yes, we should save gas for rainy days. But I hate to say that it is more efficient and cheap. There is no comparison.
You are very mistaken, the energy required to compress refrigerant is less than the energy captured and delivered if COP > 1, which is the point of a heat pump. At COP 1 it is basically heat of compression and equal to a resistive heater at COP greater than 2 the heat pump captured more heat from the environment than used to compress the refrigerant.
I am not sure if you are arguing in good faith, if so here are some of the simplest resources I can find to explain how a heat pump can exceed a furnace in efficiency even when taking power plant and transmission losses into account, with easy to understand graphics:
This should really be taught and drilled in lower education, the difference between heat and temperature and relationship to power, how heat engines work, etc. This stuff basically makes modern society possible and we will never progress in decoupling our power sources from use of the power which is what electrification allows which allows us to transition away from throwing carbon up in the air for energy.
Well of course when talking about efficiency you have to specify what you are being efficient with respect to: what's most energy efficient might be different to what's most cost efficient which might be different to what's most carbon efficient.
Cost is going to vary greatly on the electricity and gas prices in your area, so it's hard to give a definitive answer there.
With regards to energy efficiency, my understanding is that heat pumps can be up to 400% (300% typical), which is naively much better than gas which is at most 90% efficient (70-80% typical). This doesn't take into account the extra innefficiency of generating the electricity in the first place, but a quick google tells me coal plants are typically 33% efficient, with combined cycle gas plants being typically being 50% efficient. Even at those levels, heat pumps still look to be coming out ahead to me. And that's not even taking into the possibility of green energy generation through renewables or nuclear.
Yes, heat pumps do win. They win even more when you consider that the energy mix is not 100% fossil fuels. Globally something like 15% of energy comes from renewables or nuclear, plus 20-ish % from natural gas which is, as you said, 50-ish % efficient in turbine power plants.
My father has solar and a heat pump. His cummulative heating and electrical cost is practically zero over the year. On many days the solor panels produce more than he can use so he gets money for feeding it into the grid.
If the roof of your house produces enough electricity for the people living it and the heating (and cooling) of all rooms, it is a no brainer to switch to a form of heating that relies on electricity.
Don't you want to resist to turn to explanations like this, that require some invisible force to pull the strings? I think there are more realistic ways to imagine this happening.
If for example a pop star is getting a lot of attention, in multiple countries, what is the mechanism behind that? And is it orchestrated?
Explanations like what? Op didn’t put forward much in the way of hypotheses. If you have a good explanation of the mechanism by which attention accumulates around topics that doesn’t require orchestration it would be interesting to hear, it seems like a poorly understood phenomenon.
The way I read it, Op was suggesting a flirt with conspiratorial thinking ("someone is doing this") and I wanted to turn to something more rational.
I don't really know how trends and fashions form and haven't thought so much about it. Some aspect of it might look like research into the ising model and phase transitions - small changes in "temperature" everywhere in the mass of people might look like a phase transition in the overall mood.
It’s called: product market fit. When people like your products, they talk about them.
I have heat pumps through a mini split system. I like them so much I’m redoing my entire HVAC to add ducts with heat pump powered heating and AC. They’re kind of a miracle: they produce great heat (way better than a gas-powered furnace), they’re ultra-efficient, and they’re whisper quiet.
I'm just annoyed that I was talking about heat pumps for the last five years or so and nobody is giving me any credit for running an international conspiracy.
But seriously, it's just the next fish to fry after electric vehicles became a solved problem. Heating buildings is somewhere around 10-25% of total emissions and probably the largest remaining single factor not directly addressed by switching the electric grid to renewables, so many people concerned about climate change have converged on it.
There was a push towards renewables and heat pumps after Crimea too (and before, for general climate change reasons)
There was also push to do the opppsite to neutralise that threat to fossil profits e.g. Bjorn Lomberg the skeptic saying that we didnt have any tech that could replace gas, so the only response to Crimea was to frack or invent totally new tech, not rolling out renewables and heat pumps faster.
> Still, many EU politicians talk mostly about expanding renewable energies as a way of making Europe independent of Russian energy. Connie Hedegaard, the European Commissioner for Climate Action, said the Ukraine crisis should be a “wake-up call” for European countries to make the switch from Russian gas to clean, renewable sources of energy.
> But this simply ignores reality. According to the International Energy Agency (IEA), Europe gets just 1.3 percent of its energy from renewables like solar and wind, whereas it gets about 75 percent from fossil fuels and most of the remainder from nuclear. Even an extremely optimistic scenario from the IEA suggests that by 2035, Europe will only be able to generate 8 percent of its energy from these renewables. Focusing on them is simply populism without realism.
At that point, climate skepticism was strong enough politically to prevail. They tried to use this latest annexation to promote fracking etc. too but it seems to have largely failed.
You should expect this impression to become more intense. How else will you heat your home without emitting greenhouse gasses? Electric space heaters are vastly inferior for obvious reasons. Everything else is out because we eventually need to achieve (net) zero emissions. And since there are a lot of gas and oil heaters to be replaced, heat pumps will only increase in demand.
1. There was recently a statement released by a member of the Consumer Product Safety Commission saying they were considering regulating indoor pollution from natural gas stoves. This lead to a bunch of outrage and claims that Natural Gas was going to be banned at a Federal level. https://www.washingtonpost.com/climate-environment/2023/01/1...
2. Cites like NYC have implemented bans or limits on new gas installations, and it has been proposed at the state level as well. Other cities such as Chicago have had conversations regarding this issue, at least enough for it to get into the news and spark minor outrage.
Because of these recent controversies there has been much talk about Heat Pumps and whether or not they are able to function efficiently or sufficiently in sub zero temperatures regularly seen in the upper Midwest or North East.
YES. There is a massive electrification push right now because electric items can be fed from "sustainable" things like wind/dam/solar and don't emit CO or CO2 in operation.
Heat pumps are also inexpensive on initial cost and less expensive than straight AC with gas heat.
They are also low maintenance in comparison to straight AC with gas heat.
This hasn't been my experience. I can get an AC unit and gas furnace installed for something like 7k. But a heat pump unit that heats and cools is something like 13k installed. I obviously went with the former.
That's fascinating and I believe you were subject to some weird market conditions there. Look at the complexity of gas burners vs a reversing valve and electric heat strips and I think you will see what I mean.
The challenge is there aren't a lot of options for heat pumps in many US markets it seems. There's really only higher end units available, so there's no range in prices.
I priced out a heat pump versus just an AC and gas furnace in my area, and it was a similar spread a few years ago for me in Texas.
The install price is only the start. The total cost of ownership over expected lifetime is the important number for many. That initial 7K installation cost is only a fraction of what you’re going to pay in gas and electricity over the next decade.
Very true. Simply having gas available to use results in a base bill for service, even if your usage is zero.
And yet what I see time and again is that initial purchase price is the only focus for construction costs, even rehab work. Those budgets are a separate bucket from utility bills so lower priced projects get approval even if utility bills will be higher.
It's worth mentioning that the Inflation Reduction Act is now providing for substantial subsidies for purchasing heat pumps (and other home electrification projects).
How long do those units last, though, and what is their operating cost over their lifetimes? TCO obviously includes more than the initial cost of the equipment.
Gas heat probably should be tuned up for clean burning every year or two. A heat pump is generally good for years until something breaks. Both systems need filter changes and coil cleaning, which most homeowners can do themselves.
Couple "fun" things about a heat pump; You will smell burning the first time the electric strips are used every year moving into the heating season, it's just dust burning off. Once you start moving into colder weather you might notice the system changing into defrost mode so it can melt ice off of the outside coils. There's a variety of sounds that accompany this and you might even see a bunch of steam coming off of the outside unit. It isn't smoke and it's normal. Every year there's a flood of 911 calls about this.
I’ve been independently interested in heat pumps because I need to replace my old end-of-life system and I’ve been interested if a modern cold-weather mini split system is a better investment. There’s lots of conflicting info I’ve found on if heat pumps perform in freezing weather and at what kind of efficiency.
So largely I think the confusion stems from there being two major different "types" of heat pumps and they perform very differently.
The first is your conventional type system, this is usually what AC units are in the US. They run at maybe 1 or 2 speeds. These type of heat pumps are common in the southern parts of the US but also will be found paired with a gas furnace in the northern US. Since they don't adjust their output dynamically they tend to start losing capacity/efficiency significantly around 25-30F.
The second is an inverter driven heat pump. You usually find these in mini splits but they can also be found in a standard air handler form factor that would replace a furnace. The inverter allows the compressor to adjust based on demand and exterior temperature to maximize efficiency. This allow these units to operate efficiently down to -13F depending on the unit. Now there will still be some capacity loss at those temps so during the design of the system this has to be taken into account.
For detailed information on the efficiency of heat pumps I would check out NEEPs website. It is a great resource, it will show you capacity and efficiency (COP) of tons of different units across their operating temperatures.
I’ve got a mid-range Amana heat pump and even that has a COP of 2.1 (2 watts of heating per watt used) down to 0F.
Heat pumps require different system design than a traditional setup, where the cooling load is usually the driving force. You might need a bigger heat pump to handle the heating load in very cold weather accounting for the efficiency loss.
It's a great way to lessen the demand on fossil fuels and the power grid.
Manufacturers are obviously pushing, but many utility companies and municipalities are too. Basically the electric car or solar panels of HVAC. It's one of those things where there are a lot of incentives for everyone involved all the way down the line.
Just the hivemind I guess, doesn't feel coordinated to me but rather obvious. In my country the waiting time for heat pumps is now over a year. People can't stop talking about energy, the war and their utility bills. Heat pumps are very on topic.
This is, of course, the regulation as it stands today; things can always change. Additionally NYC alone likely doesn't account for the attention. But, other metros and municipalities could have similar legislation.
I see this as well and it looks to be multiple people buying in to the campaign, especially here on HN.
Having lived in a new, high end apartment that had a heat pump for both heating and cooling for 3 years, I am very unimpressed with the tech. Running nonstop, couldn't heat/cool above/below a certain threshold. Electric bill very high. Clogged and broke a lot. If the general radiant heat and cooling from being in large building didn't exist, I couldn't see this working halfway decent in any place in the midwest. This might work for areas with less variable temperature ranges but for the midwest USA, not seeing it.
Your singular experience is an outlier, not an example of totally normal circumstances.
There is no conspiracy to push broken technology on to the masses. Heat pump technology has come a long way and modern heat pumps are very good at what they do.
If someone installed a heat pump that doesn’t work in the temperature range of your location, they really screwed up. Modern heat pumps can be selected to work down to very low temperatures, and they’re installed with auxiliary heat when necessary. The design parameters aren’t a mystery.
Your high end apartment must have had a low end heat pump installed.
In the midwest a geothermal heat pump would work wonderfully.
Also, they are designed to run constantly in order to maintain the set temperature -- it's not like a natural gas fired furnace where it quickly reaches the set point.
What's the payback time on something like that for a modest home in a place which can get significantly under 20 degrees (F) or over 95 degrees for weeks or longer? How effective is it at those extreme temperatures when it matters the most, and how does this affect maintenance costs?
Additionally, there are multiple types of restrictions on where geothermal pumps can be installed, and navigating this can add to costs.
I don't see it as a one size fits all solution, there are far too many people for whom the household/company math doesn't add up. However, I agree we should be doing fair comparison against other renewable-friendly options for all new construction. I'm sure heat pumps could win out in a great many situations, and we should use them where they do.
Note that a heat pump cooling a building is essentially the same as an air conditioner. So it's more a matter of how efficient the air conditioner you're replacing is. Cooling a house is much easier than heating, because the temperature differences are lower. In your example, cooling 95 F to 70 F is a 25 F difference, while heating 20 F to 70 F is a 50 F difference. The world record for heat is about 135 F, which is the same difference from 70 F as 5 F, a completely normal winter temperature in much of the world.
Obviously nobody can answer the long term cost differences between gas and heat pumps, since the cost of natural gas and electricity can change drastically over the lifetime of the unit.
GP's comment was about the tech, though, and not the cost of said tech.
It's absolutely not a perfect solution for all heating needs across the globe, the the technology is far better than GP is suggesting.
In my view, natural gas is only competitive due to externalized costs and the slowdown/freeze of nuclear energy deployment. I recognize it's the only option for all kinds of situations (my dwelling heat included), but for anyone thinking forward it should be excluded in future development where possible.
My main concern is the overall long term efficiency & affordability of renewable-friendly solutions, because competitiveness in those areas is what will lead to mass adoption. The point I was hewing toward is that I feel the heat pump advocates and providers need to make it more clear which situations are best suited for that solution and which are not, because it would benefit everyone.
> Also, they are designed to run constantly in order to maintain the set temperature
Not all heat pumps are variable-speed like you describe. My own home, built in 2000, has a single-speed heat pump that kicks on 100% or off, like a regular old AC unit.
Right, what I'm trying to say is that it is normal for it to be on 100% of the time when it is cold out. If you are used to gas heat which can turn on for 15 minutes, overshoot the set point, and then be off for the next 45 minutes, a heat pump will seem strange.
Mine is a variable speed unit, but that's not the function that I'm talking about.
The constant running also affords a more consistent temperature because air is continually moving. Decreases the temperature variance throughout the zone. I have a 3 zone heat pump, 2 single room zones upstairs and a main floor with a air handler. We LOVE the setup so far.
Yes, I've been happy with ours and it was a great improvement over the last heat pump that we had.
Habits are hard to break, though, and there's not much value (if any) of lowering the set-point at night during the winter months. People still do it, though, and then the unit is working overtime in the morning to reach the desired set point.
Just to clarify, it is more efficient to lower the set-point in the winter over night. The issue is when your thermostat is set to utilize aux heat if the delta is higher than your set point change in the morning. For example. If you change from 70 to 67 at night. In the morning when the set point goes back to 70, the thermostat is likely configured with an aux delta of 2 or 3 degrees. Meaning every morning the expensive resistive heater is running to raise your temp quickly.
Personally, for my home and climate in the area, I disabled aux heat entirely, unless the temperature is below 0f outside, or if it hasn't reached the set point within 2 hours. Recently had some cold weather and these settings worked well for my home.
I'm using an Ecobee, configurations will vary per thermostat. The big settings for me were using manual staging to configure the temperatures to engage aux, temps to lock it out, etc.
1. The American market has a lot of incorrect perceptions of heat pumps. Debunking these makes for great viral content!
2. The IRA introduced big incentives for various electrification expenses.
The incentives are the big thing, but the public interest/controversy part is why some enhancements like heat pumps and kitchen electrification ("don't take away my gas stove!") are going more viral than, say, electric vehicles (technology connections guy has some good EV content, but it's not doing quite the same numbers)
Governments are influenced by what other governments are doing in a variety of ways.
At a basic level, governments are full of people who have an interest in public policy, and they read publications that cover public policy matters from around the world. If the EU brings in a policy that encourages an expansion in heat pump usage, it'll probably get written up in The Economist (and a bunch of more specialised publications), and, guess what, bureaucrats and political staffers in the UK, the US, Canada and so on will read it.
There are also institutions specifically devoted to developing policy advice for national governments, and in the renewable energy space the big one is IRENA. And guess what, they're telling their member governments that, hey, if you want to screw over the Russians, meet your greenhouse targets, and save your citizens a bunch of money, heat pumps are the way to go. And as those things happen to be basically true, national governments are falling over themselves to implement policies to encourage it to happen.
I am a happy user of a DYI air source heat pump, that I've been using for 8+ years, mostly for heating in a residential building.
First, it must be told that an off the shelf AC unit is technically speaking also a heat pump. There has been this distinction (and confusion) between AC units and (mostly) ground source heat pumps because, you know the latter actually have a water 'pump' to circulate fluid in the ground piping. Ground source heat pumps are far more expensive that AC units and are nearly impossible to retrofit in existing buildings. Hence, companies came up with a 'middle ground' solution, called air source heat pumps. In these devices the outdoor unit is much like an outdoor unit of a split type AC, but the indoor unit is basically a refrigerant/water heat exchanger with a water pump and some sensors around it. There is also a monoblock type of air source heat pump, where all components are in the outer block and you only connect the piping.
IMHO, the reason air source heat pumps are becoming popular now is because their price went down considerably during the last 5 years, whereas the price of fossil fuel heat sources has gone up. Back then when I had to choose between a gas boiler and a heat pump, the boiler was around EUR 2, off the shelf heat pump (24000 btu) was around EUR 7k and for the DIY option I paid a total of EUR 2.3k. The reason for this was that the market for air source heat pumps was underdeveloped and companies (e.g. Mitsubishi, Daikin, Fujitsu) were charging a lot more in this market segment (rich people with new houses). At some point in time, people started realizing the benefits of a heat pump over a normal AC (less units, no noise, nor air currents, better efficiency, can produce hot water, heating is decoupled from the source and more sources, such as solar can be seamlessly plugged in). Manufacturers albeit slowly responded to this demand.
Now with solar power gaining more traction, they are becoming a very obvious choice.
> worth looking at who the winners are and what the trade offs are.
The winners are consumers, the effort to reduce GHG and particulate emissions, and the drive toward energy independence (whether at the national, local, or hyper-local level).
The losers are fossil fuel extraction industries, because due to the high COP of heat pumps, far more heat is delivered per unit of energy consumed, even if that energy ultimately comes from burning natural gas at a power station. Also, the source of the energy itself gets disintermediated, since electricity can come from multiple sources, including renewables.
The tradeoffs are (for now): Higher upfront installation cost (tempered by the IRA, and potentially lower operating costs), availability of the equipment (supply chain stuff), and long delays in installation due to lack of qualified installers (and resulting high costs).
> What is going on? Is there a global push to get everyone to switch to heat pumps. It seems that there is heat pump content everywhere. Clearly there is a push.
Based on the lack of political dick swinging I don't think this is a "push". They're legitimately good technology for certain use cases, I'm sure the manufacturers are pushing them. They are also The New Hotness(TM) and they are billed as environmentally friendly. Both those attributes are valuable by themselves to some people.
I think this is more a case of a grassroots-originated circle jerk within certain demographic bubbles.
I get a lot of "air fryer" vibe from the whole thing. And I say this as someone who owns and really likes his air fryer.
Heat pump as every heating or cooling devices, have pro and cons.
This is where HVAC knowledge is nice to have, in order to have the best solutions. For example, the maintenance / obsolescence are an under estimated point when it comes to environment and savings
my friend is building his house and is putting in 4 heat pumps (big house). The problem is we just lost power for 4 days and 2 years ago we lost power for 5 days. He is discovering that electric heat uses massive amounts of electricity and there is no way to get a residential generator big enough to power them all. He might not even be able to power one (they can use in excess of 20kw).
I would never get electrical water heater, stove, and heater for that reason.
So this is one of my big concerns - I live in a cold weather country currently. We have power outages once every couple of years. If I don't have back up power my pipes freeze and then i'm out probably > $50k.
I was thinking the solution for me is to put in a heat pump and then run a backup gas generator. But that solution feels like a significant amount of overbuild. I have 3 minisplits already but they aren't valuable in the winter -- where you install your AC units isn't where you would install your heating units .. I.e. the top of my house for AC, the bottom of the house for heat.
Having multiple energy sources to defray risk is helpful.
Heat pumps are great when things are mildly cold. While do work down to -20C or so, efficiency drops off, so you need bigger and bigger units. It often makes sense to have a smaller heat pump that will only work down to -5C (random temperature, a real analysis of your house is required to give a better answer), and then a gas furnace backup for those really cold days. Once you have the gas furnace backup you can run that off of a small generator on the few days you are without power.
> my friend is building his house and is putting in 4 heat pumps (big house). The problem is we just lost power for 4 days and 2 years ago we lost power for 5 days. He is discovering that electric heat uses massive amounts of electricity and there is no way to get a residential generator big enough to power them all. He might not even be able to power one (they can use in excess of 20kw).
If he's building the house new, he should strongly consider investing in designing the building envelope in a way that 20kW heat pumps aren't required. It's very possible, especially with new builds.
The models to follow are Passive House [1] and Pretty Good House [2]. There are many examples of large houses built to those standards in cold climates that use a heat pump that only draws 2kW, which could easily be powered by a generator or backup battery. This assumes that by "big house" we mean something still below ~3500sqft and not some kind of mansion.
The basics are to get the building air leakage below 1ACH50 (3-5x better than most codes, but not hard in a new build), and eliminate thermal bridging by using thick exterior insulation around the building perimeter.
Continuous improvements in technology, growth spurt in electric motors, demand gap for automobile motor part suppliers having to seek out related industries, cheap summer electricity via solar panel meet kick in the behind by fossil fuel energy prices.
It would be great if this was coordinated. Ideas that are good for people usually don't get a very intelligent effort promoting them compared to really bad ideas that make a few people really rich.
Heat pumps are the opposite of AC. AC industry is behind this for sure. It is like a paid PR campaign. It is not more economical then gas. So now gas is going to be punished for factors X,Y,Z.
It is coordinated. I wish there is more investigative research into who and why they are doing this.
For the record, I am only trying to make my elearning website more known. There is plenty of other HVAC subject that I would like to share.
It's just that Heat Pump where for me an interesting topics to get into the subject but you can have a look at other free courses.
Ah yes, "big AC" is bullying the Oil and Gas industry with their subversive marketing. If only Exxon, BP, and Shell had some political clout they could expose this plot.
The whole bit about gas stoves I have no doubt is a pretty typical astroturf campaign from the fossil fuel industry. They have shamelessly made up pro-gas nonprofits using fake personas, paid social media influencers to promote gas stovetops, and are likely behind the current "gubmit wants to take away your gas stove" trend that's drumming up online drama.
One doesn't even need to look at climate impact to say gas stoves are bad, but focus the narrative on that one aspect and you can get climate deniers hyperventilating and defending their gas stovetop with statements like "you'll pry my gas stove from my dead hands". But really, economics are going to kill them all the same - induction stoves are dramatically more energy efficient, have the same benefits of fast thermal response, and don't pose a gigantic risk to life and limb every time you turn them on (or leave them off, for that matter).
Gas stoves bad, yes. If you do a modicum of research you can see that they cause indoor air pollution (and most people don't have real hood vents to outside the building).
I think the underlying reason for it is that lots of engineering types got air quality sensors during corona, and noticed PM levels spiking from cooking. Or just people getting more IAC-conscious in general.
This technology connections YouTuber I've seen pop up in lots of discussions on these topics.
That's what is funny to me too -- they're basically phasing out all furnaces and hot water heaters that aren't direct vent (bringing in combustion air from outside) because it's so problematic to have gas-burning appliances in your home. Yet we just burn gas stoves -- some of which are massive without question...
Apologies that link was broken -- but that was a "Commercial Style" stove for a home, not actually a commercial appliance. In any case vents are a really bad solution.. but they're inefficient at removing fumes, are usually undersized and too far from the cooking surface, and most people don't use them because they're obnoxiously noisy when running at the proper speed.
A friend of mine just remodeled their kitchen -- they got all the permits and sign-offs, and their AHJ allowed a gas stove in the island with no venting at all. Inspector told them they should open a window if they were doing a lot of cooking. It's actual madness.
Is it a "solution" when it's completely optional and rarely done correctly? This whole discussion reminds me of the 80s TV interviews that made the rounds this week about people complaining the government was infringing on their right to have a beer in the car on the way home from work (https://www.tiktok.com/@cali_nostalgia/video/719704298970805...).
"It's my god given right to poison my family with CO and NOx!"
Yeah, tl;dr: fuel price scares and the French nuclear power plant disaster, as well as government regulations.
To expand: most homes traditionally are heated by either burning something fossil (oil, gas, coal), somewhat half-ish renewable (wood pellets, straight chopped wood), by straight electricity (resistive heating) or by heat pumps (air-to-air, ground-to-air, deep-well-to-air aka geothermal). Some homes particularly in urban areas or in close proximity to a large power plant can also be heated by district heating using one of the aforementioned heat sources.
And all of these classes of heaters have their issues:
- Electricity is the easiest of the bunch from a technical point of view, but you're out of luck when the grid fails for whatever reason, you're tied to grid price hikes in some contract models (as people learned the hard way in Texas' last winter spike), there will be fuel burned as part of the generation and frankly resistive heating is wasteful.
- Wood pellet has the problem that the amount of waste (=sawdust) is finite, which means you're chopping down wood that could be used for construction and burning it instead. That is a waste of money and valuable resources when wood is scarce, fine particulate matter causes smell and health issues, and a lot of wood is unethically sourced.
- Solid-wood or coal heaters are difficult to properly fire up - most people fire it wrong (not enough oxygen / too much fuel load), resulting in higher consumption of wood, higher emissions and a danger of soot buildup which is a fire risk. Additionally, many home fires are started by people disposing not-completely-cooled ash or placing flammable objects too close to the oven or exhaust, and still a lot of people die because of carbon monoxide emissions caused by improper handling.
- Oil stinks to hell and beyond, the boilers need an insane amount of maintenance so they don't clog up, you need to ship tanker trucks to homes, there are risks of spillage and contamination, and the same emissions issues of wood apply (plus, oil generates more CO2 than gas per kWh of heat). Also, it's not renewable at all.
- Gas is relatively easy to ship around when there is a gas distribution network in place, it burns relatively clean, but carries an explosion risk and is fossil in origin (at least for the next decades that it will take to build up power-to-gas infrastructure).
In contrast, heat pumps are pretty awesome:
- all they need is a bit of electricity - a good heat pump can achieve up to 4x ratio, meaning it generates 4 kWh of available heat in the home by using 1 kWh of electricity. That also makes off-grid or local generator fallback solutions more feasible - a 20 kW heat-pump boiler needs a 5 kW generator which can be had for a couple hundred dollars instead of a massive generator unit.
- their heat sources (or rather, cold sinks) are renewable - air, local ground loops or deep wells are virtually infinite. That means, as long as your electricity supply is renewable, your heat generation also is renewable.
- Most heat pumps run at 40-ish degrees. That in turn prohibits the use of old-school convection radiators, so most installations with heat pumps tend to use floor heating which needs less energy to achieve a temperature comfortable for humans (our feet are the most sensitive part, but as heat from a convection radiator rises to the top of the room, it needs a lot of energy for a comfortably warm floor).
- they are, particularly when compared to oil heating, extremely small and don't cause emissions
- they don't need much maintenance effort to keep running, and no need for chimney sweepers either
- they don't pose an imminent risk of carbon monoxide poisoning or outright fire
Basically, the only issue heat pumps have is you need specially trained people to install them and they are short in supply at the moment since everyone and their dog got shocked to heaven in the last year of that goddamn war and heat pumps are the objectively best way to heat a home.
topic of discussion: is anyone else concerned that all the new things being clearly pushed hard, regardless of reasons(good or bad), has the common theme of centralizing. In a world where if your heatpump stops working, you die from cold, it would be an awfully sad thing if social credit scores dictated a very low kilowatthour limit. Much more sad than a world where you obtain firewood from some local vendor
I am not sure the case you are making here- most people who would be switching to a heat pump for heat are almost certainly using oil, natural gas, or propane to heat their homes, all of which require a good deal of centralization.
Those that have the ability to use firewood to heat their homes today can continue doing so if they need to- its not a requirement to close up your chimney permanently to use one.
FWIW I am considering switching to a heat pump, but would still have natural gas fireplaces as a backup.
> has the common theme of centralizing. In a world where if your heatpump stops working, you die from cold,
Using machinery for heating isn’t new. Virtually nobody in the modern world uses firewood from a local vendor to heat their homes.
These conspiracy theorist angles are baffling. Heat pumps are just another variation of AC, which is already ubiquitous. If people don’t use heat pumps, they won’t use firewood. They’ll use a regular furnace or electric heat.
> Much more sad than a world where you obtain firewood from some local vendor
A while ago I ran the numbers, and to meet UK electricity demand from wood would consume every single tree in the country in three months.
Limiting that to heating and giving up on industry would stretch that a bit, but the country is fundamentally dependent on imports to stay alive. We can't not be global.
Did you know that installing a heat pump doesn't magically cause fireplaces in the house to stop working? Or that if you're concerned about being cut off from electricity because of your low "social credit score" the heat pump will run just fine off solar panels and batteries?
It is coordinated. In many states there are huge incentives [1] to disconnect your existing home from (and not connect new construction to) the natural gas infrastructure.
This is great for the climate but air source heat pump technology simply doesn't work well in cold climates. Most heat pumps in the United States have 100% efficiency down to about 20 degrees F. Below that they "lose efficiency."
What most people don't realize is that "lose efficiency" = blows cool or cold air. So if you live somewhere that routinely gets that low you are likely either going to be really cold, or have to engage aux heat (often natgas or oil-based heating or electric resistance heating).
Additionally, even when operating at 100% efficiency they don't blow air as hot as traditional heating sources. So if you have a poorly insulated room, large space, or even just an unusually cold day, it will often have a hard time keeping up.
I have found that I only use my air source heat pump a little bit during the fall in New England, and I have to run aux heat throughout basically all of winter. Talking to my friends in the region who have heat pumps, they all have similar experiences.
I think we are all very eager to get off of fossil fuels but the technology just isn't there yet, and I am concerned that most people installing heat pumps today don't know the risks associated with them in extreme weather events. If your heat pump can't keep up and you didn't install aux heating you can't live in your house, your pipes will freeze, and you will generally have a bad time. If you did install and use aux heating, you may be surprised at how expensive and inefficient resistive electric heating is as it may need to run all the time.
This is FUD. I live in climate zone 5 in a 100 year old house that has high heating demands and our air source heat pump has been awesome, even when it dipped into the negatives briefly this year. Our heat pump is over 100% efficient down to 0F.
Definitely a lot of posts about heat pumps on HN recently that this topic has piqued my interest but only to the point that I want to know if I can install one in my home. Are there any legit resources out there that can help me understand if heat pump is a right choice for my home based on Geo, type of home, sqft and other factors to consider before replacing current systems (two ACs and two furnaces?)
Generally, they can work anywhere in the continental US. (Assuming you live in the US.) If you're in northern NH, NY, VT, or Maine, you might want to keep your gas system as a backup. (New homes tend to have electric backup, but if you have an older home they just keep your furnace as backup.)
I have a 3000 sqft house in MA with a heat pump as my primary heat, and an electric strip as backup. The heat pump goes into the ductwork for most of the house. I generally haven't had problems. (It did have to be adjusted because it was the first time the installer put one in.) I have solar and usually get 1-2 large bills in January and February, and then March and April are very cheap, if I get a bill at all. My "large" January and February are comparable to what I'd spend on conventional heat.
Last weekend we had a "once in a century" cold snap down to -4. Most of the house was at temp, but one room fell to the high 50s. From what I've heard, plenty of people with conventional heat had far worse issues than a chilly room.
Around Vancouver our heat pump has performed adequately even down to -15C/5F. This may be related to it being a deep ground loop geothermal setup (vertical instead of horizontal), and the type of building (concrete). We do have a gas fireplace as backup, but have not needed it at the temperatures we see in this corner of the world.
It is definitely related to it being a deep ground loop geothermal setup. An air-to-air heat pump is trying to get heat out of air that has less heat as it gets colder. A ground loop heat pump is trying to get heat out of water that is not affected by the temperature of the outside air.
With an air-to-air heat pump, you need a backup system for when it gets too cold out for the heat pump to pull enough heat out of the air, and for power outages. With a ground loop heat pump, you only need a backup system for when the power goes out because the ground water will never be too cold for the heat pump to pull heat out of.
When I built my house, I called around and it didn't sound like geothermal works very well where I live. I suspect the reason why I was talked out of it is because my yard is very rocky.
North Dakota and Minnesota are on average colder than the states you listed. I would also include Montana, Wisconsin, Wyoming, and Idaho as states where you should be concerned about performance in sub zero temperatures and have a backup heat source.
If you already have a central AC system, a heat pump is more or less a drop in replacement. The heat pump becomes both your heat and AC unit.
Heat pumps are now the most premium option on units offered by the well known names in HVAC- Trane, Carrier, etc.
In terms of suitability for your climate, they should work just fine for most people- they start to struggle if you are in an area when temps get down to about 10 degrees Farenheit, though they improve in this area each year. Even if you live in an area that cold, there are options to mitigate this- leaving your current furnace hooked up to be turned on during those cold periods, etc. What it comes down to is it just gets more expensive if you live in these colder areas, but over time the energy savings should give you a return on your investment in less than ten years.
My Air conditioner blew this fall, so I am actively in the process of getting bids for heat pumps.
My $0.02 are that any competent and honest HVAC company will be able to walk you through the concepts of your home's heating/cooling load etc. and what size heat pump can meet that need, what it costs to run annually, and what incentives there are. It's not that hard. I would reach out to three highly ranked (or word of mouth suggested) HVAC co's and start the conversation.
I guess they are a new thing in the US. In Europe installing a heat pump with floor heating is done for practically every new family house. It is the cheapest (for us) and nicest way to heat up your home. Though very few people build houses out of wood, unlike the US.
Engineering/perforated bricks mostly. North Germany/UK is a lot of solid red/gray bricks, not sure if new homes still use that style, since it has terrible insulation. If built with perforated bricks a home will also put a thick layer of styrofoam for insulation on the outside.
If you're in 1, 2, or 3, heat pumps are definitely the right option. In zone 4 or 5, newer cold temperature heat pumps are a good idea. In 6, 7, or 8 it's less of a sure thing, and you will likely want a backup source for the colder days.
NYCHA is currently running a contest to develop a heat pump window unit. All of the proposed units are expensive to get those contest dollars, but should come down in price after.
I have two heat pump window air conditioners installed in my apartment, with cooling, heating and resistance electrical heating: https://www.frigidaire.com/Home-Comfort/Air-Conditioning/Win.... The problem is that the tech is so poorly advertised, that I had to double-check the specs on manufacturer's website that this model was, in fact, a heat pump. Most people don't know that heat pump window units already are an option.
I'd love for NYC to mandate that ACs must function as heat pumps: the additional parts are cheap, and as America's largest market for window AC units, the NYC market would force competition for much cheaper heat pump window units.
I have seen units like that Frigidaire before, and can never tell whether it's actually a heat pump, or just an AC/resistance heat combination.
Edit: Nevermind I'm an idiot. From the spec page of that unit: BTU (Cool): 11,000 BTU, BTU (Electrical Heat): 3,500 BTU, BTU (Heat Pump): 9,900 BTU. Though the owner's manual mentions an extremely warm minimum outdoor temp: "The unit should be operated in a temperature range of indoor side 60°F - 90°F (16°C - 32°C), outdoor side 64°F - 109°F (18°C - 43°C)."
>I'd love for NYC to mandate that ACs must function as heat pumps: the additional parts are cheap, and as America's largest market for window AC units, the NYC market would force competition for much cheaper heat pump window units.
This isn't great if you want a building with hydronic heating and forced-air cooling, which is really just the ideal form of both technologies — hydronic cooling creates condensation, while forced-air heating smells bad and leaves you with cold feet.
Also, I found that Home Depot's website tends to be pretty clear about which window units are also heat pumps.
A portable machine to provide heat and cooling via heat pump technology.
For cooling this exists in many forms: there are the window air conditioners, and "portable" window air conditioners which have a duct that connects to the window. The problem with the latter is that they're loud and the ducts result in a lot of heat loss.
For heating there are some portable air conditioners that use a heat pump but they're subject to the same issue described above. More common is resistive electrical heat in the form of coils or an oil filled container that radiates heat.
A portable mini split, where it connects through the window would give you a similar advantage as a portable air conditioner, but with more efficiency and being less loud.
There is a portable mini-split that recently came onto the market, and its form factor is similar to that of a window AC: https://www.gradientcomfort.com/
The only problems I can see are:
-Size/Price ratio: The tonnage (9,000 BTU) is relatively low for its price--it can only condition a ~375 sq foot space. Though the lack of install costs probably makes up for this unless you're doing a DIY job with a Mr. Cool Ductless HP.
-Incentives: Utilities may not want to spend energy efficiency incentive dollars on these, since someone could easily move and take the heat pump outside of the utility territory; which is not a problem with permanent HVAC installations. Might be covered by the IRA's rebates for Heat Pumps though.
I believe you are describing something like this:
https://mrcool.com/u-shaped-window-a-c/
Never used one myself but they are meant to be much better than the ones with ducts - you don't lose so much efficiency from the ducts or from badly patched up window openings.
yeah, exactly. there's a company called MRCOOL that does something similar (https://mrcool.com/diy-4th-generation/), but the head (the indoor part that provides the heat/cooling) is designed to be mounted permanently
if this were popular you'd see old houses retrofitted with pluggable holes where you could feed the lineset through and seal as necessary for temporary heat/cooling, or perhaps even permanent.
the installation would be substantially easier if these were like 6000BTU instead of minimum 12000BTU per head, so it could be run on say, ~8 amps and be plugged inside.
Coolant supply and return, both fully insulated. And condensate drain line, and power wires, and control wires. Do-able, but more complex than one might initially think.
The issue is that cold should be supplied near the ceiling, while heat should be supplied near the floor. So this unit would need two separate terminals or suffer inadequate performance in one of the modes.
I live in SF Bay Area 20 minutes south of SF and I don’t have and don’t need A/C, so my HVAC needs are met by a gas furnace that is 10-15 years old at this point but it still works.
Another caveat is our electricity ranges from 30 to 35 cents per KWh and is probably second to Hawaii in terms of cost.
So I do check the cost of operating a Heatpump in the winter and due to high cost of power I am sticking with our gas furnace.
If and when I go solar, I may reconsider, but for now gas is simply cheaper
As high as that is, it looks like the price of gas in SF is (relatively) even higher. $4.50 a therm per Google, or $0.15/kWh. A heat pump would only need a COP of 35/15=2.33 to be a better deal (very likely since it will never be that cold in SF, and you get air conditioning for the very few days you might want it).
TL;DR a heat pump isn't worth it in Vancouver, BC, for me anyway.
As a counterpoint to what seems to me like extremely high rates for electricity, as of right now in Vancouver, BC, Canada, I recently calculated that a heat pump would cost about ~2.5-3.5 cents per kWh of heat energy vs ~4.5 cents for gas heating at 80% efficiency. Power on average is about $0.10 USD per kWh here and gas is about $10 USD per GJ.
The average house here uses 74.3 GJ of gas per year, or $ 743 USD of gas. We would save 413 $ per year by switching over.
The neighbours next door spent $ 17000 USD to install a multi-zone heat pump, which still doesn't exactly cover every room. It's a Samsung, so by the general sentiment about their appliances here, we'll assume it doesn't last longer than 15 years and needs to be replaced at a cost of 12000 $ USD down the line.
The hot water, low efficiency 80% boiler has lasted 35 years so far. Total cost of maintenance and repairs has been under $1500 USD. We expect it to last another 30 years easily because there is absolutely nothing special, fragile, or expensive in this system. Most of the spare parts can be found by walking down the alley and seeing which neighbour fell for the "replace your heating system" salesman tactics.
If we replaced it with a "high efficiency" condensing type, we would save at most 20% on our gas bill (143 USD a year). The cost to install will be easily $5000. As a reward for doing so, we will have to pay for maintenance every 5 years at $200, and the device will fail and need to be replaced for another $4000 after 15 years. This is a statistical and practical certainty because condensate is corrosive.
For the next 30 years, the old boiler we have will cost 23790 USD in total.
Upgrading to a high efficiency boiler will cost us $28032 USD in total, not including ANY breakdowns
Using a heat pump will cost $38900 USD in total, not including any maintenance, which you ABSOLUTELY need to do otherwise it smells and grows mould. (we do this maintenance ourselves but the design of the unit is ghastly, I curse the designer out loud every time I think of it, and this is a MAJOR pain to do.)
Based on this math, there is absolutely no reason we would ever consider making any of these changes. A plumber tried to suggest something like this and they seemed to agree.
With this said, I have a heat pump in my room, originally installed because I had too many computers and I needed air conditioning. We bought the absolute cheapest unit we could find at 700 USD and it has been wonderful. It has a capillary tube instead of an EXV because it's cheap, but it works "fine" down to -5 and it rarely goes under that here.
The greatest benefit of a heat pump has nothing to do with energy efficiency or savings. The greatest benefit is that every room can have their own heating and cooling controls that respond FAST. I turn it up and down all the time when I feel like it and it's wonderful.
Do your calculations include the changes in utility prices?
I don't know if this is the right place to look at, But over the last 30 years, in BC, the "Electric power selling price under 5000kw index" has gone from 56.8 to 120.9, about an increase of 110%.
Genuine question that I haven't been able to find a clear answer for: are heat pumps now different from air conditioners two to three decades ago? (other than the fact that they heat and cool)
Memory is fuzzy but I remember when I was a little kid and even captain planet cartoon showed air conditioners being bad for the environment...
Or is it that heat pumps are better than the fossil fuel counterparts and so if you're going to do something bad you might as well do something less bad?
> even captain planet cartoon showed air conditioners being bad for the environment
That seems like it was a useful simplification for a children's cartoon, but things aren't that black-and-white.
1. Without air conditioning (or some other method of cooling and humidity control), almost all high-occupancy buildings would reduce their effectiveness as a work-place or living-place. OSHA has guidelines about office temperature (68-76, iirc), humidity, and overall air quality (e.g. pm2.5 levels).
2. The 1980s-era backlash against air conditioning was likely inspired by then-new knowledge about atmospheric ozone depletion. It was known that CFCs and bromine-containing compounds contribute to ozone depletion. It just so happens that CFC were common refrigerants (and aerosolizing agents). Refrigerant leaks from an air conditioner in those times released nasty stuff. CFCs are very rare (and restricted) in modern air conditioner / hvac systems. We instead use other chemicals which are not ozone depleters. (Though I believe that the theoretical performance of modern refrigerants is often not-as-good as the old CFCs.)
3. Running the air conditioner in a single family home is not terribly efficient, as (in most single family homes) most of the home is just empty space. Cooling bodies directly (e.g. cooling blankets, misting fans, etc) is more energy-efficient in these situations. Perhaps the more nuanced advice would be to use air conditioning to make the space "tolerable" but use direct cooling to make a space "comfortable". (This advice also applies to heating a space. I keep my thermostat between 60 and 65 and use blankets, small electrical resistance heaters, and drinking hot water as ways to temperature-regulate.)
I don't know how well they work. I have a sibling with one that they use frequently, but that sibling is a bit odd. (I think the blanket circulates water through it, but I've never really asked.) Their use may just be due to a placebo-esque effect.
Heat pumps are much better for the environment compared to the other sources of heating. Depending on where you live, you still need to heat your place and if so, heat pumps are better than other traditional methods like natural gas, wood, oil, or electricity.
Similar to air conditioning, if you want to minimize your impact on the climate, you could set your temperature lower in the winter and put on a few more layers and/or set the temperature higher in the summer to minimize your usage of heat pump/air conditioner. This puts less pressure on the grid and demand for electricity generation.
Captain Planet is not a reliable source of information. Air conditioners use electricity, the generation of which can cause fossil fuels, but also can come from other sources.
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I’ve had Mitsubishi heat pumps in a condo in the northeast for 3 years and they’ve worked great. No other heating sources here. I keep them on all day, which the mfgt discourages. My main gripe was their kumo cloud and Wi-Fi connectivity but they’ve since fixed firmware and the cloud side and it works much better.
I have seen repeated claims of heat pump CoPs improving over decades. Can anyone summarize or provide links to what improvements are being made? Compressor technology? refrigerants? Fans to move heat? all of the above? Where is the path from here?
I can provide a likely incomplete summary of the improvements.
Compressors themselves have gotten much more energy efficient, although I'm not sure the impact on CoP is all that great since and waste heat from the compressor is being deposited in the home anyway. Variable speed compressors are the most efficient you can get pretty much.
Refrigerants have improved in someways, but not really in others. Since heat pumps could be running with exterior temperatures that are quite low, with the system under pressure, some refrigerant blends would have less than desirable vapor pressures leading to problems running in very low temperature conditions. For the most part, the changes to refrigerant blends have been related to their Global Warming Potential (GWP).
Expansion valves are a very important piece of a refrigerant loop, these used to be fixed orifaces. Nowadays these are dynamic, meaning they can increase efficiency of the system by metering the flow based on system load and other characteristics. These are called TXVs or Thermostatic Expansion Valves. Electronically controlled expansion valves are now hitting the market further increasing efficiency.
Finally there is the design of the interior and exterior coils. I dont think materials have changed much, but the surface area has changed. You may noticed a 2 ton unit from 1997 is about 1/4th the size of a 2 ton unit from 2022. More surface area on the coil for the exterior unit lets you extract more heat from the air without burning a ton of energy running the fan super hard.
Interior air handlers have probably improved some as well, variable speed motors, etc. Variable speed really is nice because you can get much more consistent temperatures in the home and wont get blasted in the face with heat from vents when a regular system cycles on and off.
refrigerants (though some regulations have negative impact on this),
Optimizing (DC motors and computers with sensors figuring out what is the best setting),
Absorbing waste heat from the process,
Insulation,
Materials that stay more clean or self clean.
As someone who lives in the northeast and has a 3600sqft home, I'm wondering how many heat pumps it would take to replace my gas steam boiler system. I'm not sure if heat pumps would be cost efficient given those parameters.
One* heat pump will do fine, but you might need a low temperature heat pump depending on where you are. After you factor in that gas is cheaper than electricity per kWh, the system should save you money as long as it is running at an efficiency higher than ~130%.
A contractor should be able to select an appropriate system for you, but if you want to do it yourself, look for yourself, get the 2021 ASHRAE climatic design conditions for your area and choose a heat pump with a minimum operating temperature which is lower than the coldest month 99.6% heating drybulb temperature (DB) (should be the top row, left most temperature).
*You would also need a fairly large heat pump, perhaps 7 tons (tons here means tons of refrigeration, or how many tons of ice the system can melt per day) depending on how well insulated you are.
In the Northeast with that much square footage, you would be better off with ground-source heat pumps (whether open or closed loop), rather than the normal air-source heat pumps.
I guess the concern I have with all this is that my current system works well, and I don't want to spend $10K+ unless it brings down my heating costs significantly. Could a ground-source heat pump system do that?
Ground source/geothermal would significantly reduce your heating costs but it would be significantly more than 10k. For that large of house something like 40k+ wouldn't be out of the question, with the largest expense being drilling.
I personally think geothermal is great, sadly New England's geography makes getting a ground loop installed more difficult. In the midwest lots of people would do a horizontal loop by trenching like 8 feet underground laying pipe in there. In many parts of new england that isn't really viable with all the rock so vertical drilling is used which is significantly more expensive.
My brother-in-law lives in NE and has installed mini-splits and has overall enjoyed them. A ground source system would be "the best" for that region, but if you're not doing a new build then air source works just fine there with the correct equipment.
I also live in NE and we recently installed a mixed system. We have mini split units in the upstairs and a ducted air handler in the basement all attached to a cold weather heat pump outside. It has be working great for us so far, but we have the advantage of having a smaller house so we only needed one 4 ton unit outside.
Our house was built in 1973 and originally had electric baseboards and then was converted to an oil boiler with hot water baseboard. So retrofitting a heat pump was an interesting task.
A typical air-to-air heat pump has a CoP of 4 but the CoP goes down with the outside air temperature until the CoP becomes 1 at around -20C. Below that temp, you're better off using a backup heat source.
A ground-source heat pump typically has a CoP of 5 but the CoP doesn't go down with the outside air temperature. Because the ground water temperature is stable, it will maintain its efficiency when it is cold outside. Of course, depending on the R value of your house, it may need to work harder to make up for the heat loss through the walls, roof and windows.
You really need to find a heat pump installer who has the year round temperature data for your area and can do the math to calculate whether it is worthwhile to spend the extra on a ground-source heat pump.
Like other commenters said, a GSHP will work excellently in terms of keeping you comfortable at a low ongoing price, but your initial costs will far exceed a $10k budget and you will likely never make that investment back ;-)
The heat pumps are one of the means of heating (and air conditioning) in the heart of the news. What is their principle of operation. You can ask questions here if there are points to clarify in the course
I'd like to get a heat pump to replace my existing baseboard hot-water system (currently powered by an oil furnace) without converting to a heated air system.
From what I've read, that's not quite feasible yet, since current systems can't produce a high enough temperature.
What are the prospects of that technology becoming viable in the next few years?
It partially depends on your climate. I’m in Portland, Maine, so for us, we have a natural gas furnace with radiators, but they’re heavily supplemented by a few heat pumps. For us, the temperature frequently gets very low in the winter, sub 10°F, and this is the point when heat pumps aren’t as efficient. An ideal set up in a small home could be heat pumps running off solar and a woodstove for when it gets really really cold.
Figure out the minimum flow (supply) temperature that can meet your building heat loss on the design day. If you have enough radiation, you might be able to get by with 135°F flow.
I have baseboard in the attic and cast iron rads on the main level. I have the flow set to 126°F until the outside air temp drops below 30°F and then I increase by 2°F for every 4°F change in OAT. So at 2°F OAT, I have 140°F flow.
That’s enough to maintain temp in my fairly poorly insulated 1920s house near Boston. It’s enough to slowly recover temp as well.
140°F is a stretch for air to water heat pumps, but you could reasonably use an A2W for most of the year and supplement with a 9kW (31KBTU/hr) electric boiler as emergency supplemental heat and use that a couple days per year.
What killed it for me (and the reason I have a fairly new gas boiler installed) is the upfront cost was utterly uncompetitive.
If you have a condensing boiler, set the high-limit or flow temp to 130-135°F and see how your house handles it on the cold days. You can measure and calculate all you want, but nothing beats trying it.
This guy is a great resource if you want to understand what goes into a proper A2W system install. In Europe, it seems by law they are required to do heat loss calculations to size an install. In the US, it seems to be a little more loose. https://www.youtube.com/watch?v=0IvGe4JZLSU
I saw a video recently from a ... less sophisticated place in the US... where the HVAC installer literally held up a piece of paper from the street with different sized houses on it, and sized the HVAC based on which of the houses best "covered up" the actual house when looking through the semi-transparent paper. Just astonishing. No consideration at all for the build quality/insulation details, no adjusting for the distance from the road, just a "welp, this looks like a 3-ton job".
That's insane. Proper sizing is paramount, it's also a good way to surface that 5k in insulation improvements might be the better first step to consider vs installing a larger system just to keep up with losses.
What works for me in the northeast with an old house is a high velocity small duct air handler/distribution system (unico) coupled with a Bosch cold climate heat pump, with an oil furnace backup. This is forced air, so not exactly what you are looking for and I get that the heat from those baseboards is a better quality/less drying form of heat. I could upgrade to add a whole house humidifier to address this a bit. I use the heat pump most of the year, down to an outside temp of about 25F, although Bosch says I should be good down to 5F. The oil furnace runs basically Jan/Feb (but not as much this Feb as it's like 50F today). I've also extensively sealed/insulated the house (although there's always more of that to be done in an old house). It's a pretty good solution. I'd love for the air to water heat pump tech to work better, but I got tired of waiting.
As others comments said, it depends on the climate :
The problem is that the power/performance of the heat pumps decreases with the cold weather and the necessary increase in the temperature of the heating water, which obliges to keep the boiler for the cold weather.
This is a problem for the heat pumps without probable solution and little progress to wait.
The solution is to insulate the house very well so that its needs can be covered by the heat pump with less hot water. Divide the losses by 2 at least.
So CO2 heatpumps are starting to become available in the US which can run higher temperatures. But most likely the best option would be to switch to radiators that don't require as high of temperature to operate. Something like underfloor heating or panel radiators.
The other option that is common in New England is to keep the baseboard oil heat and get mini splits. Then run the mini splits for heat and if they cannot keep up switch to the oil heat.
Yep - exactly the issue. They've started shipping much more efficient baseboard systems which run at lower temps by adding more fins, adding CPU fans to increase heat transfer across the plates, etc. but the correct answer is to usually invest in air sealing/insulating the house which will require fewer BTUs in the first place.
I think this is possible. I will ask to a teacher of hvac-learning and come back to you asap. But basically you can heat water instead of air with a heat pump.
The other issue here in SF and near the coast is that for older, poorly insulated homes and those with high ceilings (mine are 12 feet), the real problem with an air heat pump is how slow it is to heat the volume. Unless you want to pay to keep your house warm 24-7 it will take an hour to warm up the whole house. I would love to kick my 10 year old forced air gas furnace to the curb, but I don't see how, even if I get solar. Contractors are charging a fortune for installing heat pumps these days too.
Heat pumps aren't meant to be turned on and off. In fact, they aren't meant to have the thermostat changed either, even at night. You set it to what you want and it keeps it there. Once it gets the temp where you set it, it doesn't use much electricity to keep it there unless it is very cold, like below freezing and especially below -20C.
Due to your high ceilings, it might be prudent to install ceiling fans to help circulate the heat, but I'm not a heating expert so I recommend asking one.
Is there a good calculator where I can enter my cost for units of electricity and gas and it will tell me how much operating a heat pump will save me over a gas furnace
To get a useful answer, you would have to put in more information. How many floors? How many sq ft per floor, what is the R value of your house? How cold can it get in the winter? How often is it that cold? Are you asking about air-to-air or ground-source heat pumps? The best thing to do is to get one or more local installers to give you an estimate.
My heat pump has a CoP of 3 and paid for itself in 10 years. New heat pumps have a CoP of 4 or higher and might pay for themselves in less.
How much material in a heat pump is recyclable and how much isn't, compared to a furnace?
We are trying to reduce CO2 and methane in the atmosphere. Throwing away the non-recyclable parts of heat pumps isn't as big of a concern. Polluting the ground and water isn't even as big a concern. Certainly they are concerns, but they pale in comparison.
The furnace in my house is from 1970 and still works. I don't want to know how inefficient it is. (I just upgraded the insulation of the house, replacing the furnace is a future problem)
No worries, I'll take a look at your site later. :) If it helps, I tried reaching the site from Norway. Thanks for reaching out! Edit: It works just fine now! Looks pretty interesting!
The site is pretty new, I(admin) am not used to have lots of traffic. I will analyze what happened and chose better solution. I am sorry for the inconvenience !
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https://www.youtube.com/watch?v=MFEHFsO-XSI