Make a cost-benefit calculation and maybe you won't feel as bad throwing it out. It will depend on financing and electricity costs which way is cheaper in the long run. :-)
I think you (and the OC) will find that, with dryers, there's really not much room to gain efficiency. It's not as if modern dryers are using a heat pump instead of burning gas [1] or "burning" electricity with resistive heating.
[1] and natural gas tends to be cheaper than electric heat pumps, especially nowadays
> there is an almost 10 year old Miele dryer in my apartment, with a heat pump.
I stand corrected. I'd be curious if it's actually any more efficient, especially if the heat it's pumping comes from gas, oil, or resistive heating (in the winter, assuming cold climate). It can appear more efficient, of course, if one only measures the dryer itself, but that wouldn't be apples-to-apples.
> Here's their top of the line current offering in the USA
$1800 is an eye-watering price. That'd buy me 3750 hours of 4kW [1] dryer usage, so buying it for long-term savings alone is hardly an obvious choice.
> clever uses of natural gas
Raising temperature by burning it seems like the least clever use of natural gas (or any combustible).
[1] I figure the least efficient resistive heating dryer is 5kW and that Miele is 1kW.
For my case, I figure it has in recent years started to give a return. I had to repair it (myself) with parts for $40 once. It has certainly been running for much more than 4000 hours.
Looking at the greater picture, the power mix here is about 50% nuclear and hydro, the rest from burning garbage in combined heat (heats the whole town) and power.
You can tell it's not using as much power as our previous dryer, the bathroom would get sauna hot if you closed the bathroom door and also the clothes would take longer to dry - with the Miele there isn't much difference with the door open or closed either in drying time or room temperature. It's also less wear and tear on the clothes. The clothes come out consistently "dry" instead of between "humid" and "extra crisp" with the old dryer.
Stepping away even further from the picture, I actually prefer hanging to dry (clothes don't wear out as fast and I actually enjoy the slight stiffness of textiles hung to dry, a childhood thing I guess) but my (soon to be ex-, thank God) wife swears by the dryer, so... a dryer it was. And I have to admit, it's damn useful at times.
You can buy a heat pump drier for less than $500 in Germany, with the premium brands' models around $700. Their energy consumption is about half that of a condensation drier. At German electricity prices (ca 25ct/kWh), it's not hard to see why heat pump driers have gained significant market share.
And for the record, the heat pump is used to dehumidify the processing air. The air is still heated using electricity. It just doesn't waste as much heat.
> Their energy consumption is about half that of a condensation drier.
Again, this is not necessarily a fair comparison, if what's being pumped actually costs something that can't be measured at the dryer's plug.
$500 would likely be worth it, even at $.12/kWh, but the market may not think so if they're not available for that price in places with cheap electricity (and/or cheap enough natural gas, which can be much cheaper, ranging between $.04/kWh and $.06/kWh, equivalent, on my last bill).
> the heat pump is used to dehumidify the processing air.
This seems a bit strange to me, but it makes sense, especially if there's recirculation going on.
> The air is still heated using electricity. It just doesn't waste as much heat.
This is pretty clear from the efficiency only being 2:1, which is much worse than what I'd expect from a heat pump being used for heating.
The only energy input is electricity. The heat pump is used to recover heat from the exhaust air. There is no other source of heat involved, so the comparison is entirely fair.
I'm a bit confused, since, initially, you mentioned dehumidifying.
However, I'm getting the impression that the heat pump in this case is entirely internal to the machine, which is not what I had in mind when mentioning heat pumps (thinking of their coefficient of performance of 3-4) [1]. Were I aware of these machines, I would have specified:
It's not as if modern dryers are using a heat pump with an outdoor source to raise the temperature of the clothing instead of burning gas or "burning" electricity with resistive heating.
That said, a 2x efficiency gain, by whatever method, is more than I expected, though still falling into what I would categorize as "not much room", especially if the gain comparison always assumes the oldest, least-efficient 5kW model only ever running at its highest setting. The other key assumption in all these comparisons is that all these dryers can finish the same sized load in the same amount of time, which can't possibly be true in the real world.
If my $40-to-repair machine already has some efficiency tweaks such that its worst-case is only 4kW, the $500 machine's worst-case is 2.5kW, but my actual behavior averages out to running them at 70% power, I'm saving barely over a kilowatt per hour, and I'm back up to 3500 hours to break-even at $.12/kWh electric rates. $1800-for-1kW is nearly 14k hours, or nearly 18 hours a week over fifteen years, and I don't do that much laundry.
[1] If this is so, it strikes me as odd to call it that, just as it would strike me as odd to call out a free-standing dehumidifier having a "heat pump", even though that's the crucial to the device functioning.
Electricity is far more expensive than gas. I would even factor the cost of not having a gas line when choosing to purchase a property. Commercial dryers, such as in hotels, are also gas. Actually, the only time I’ve seen electric dryers are in apartment buildings too old to have been hooked up with gas lines.
That's usually only if the gas is natural gas, and that's not available. Even then, "far more" can be misleading.
My experience in California is that it's on the order of 4x cheaper than using resistive heating in a residence (i.e. buying naively from the utility at retail rates).
My latest PG&E bill shows "procurement" costs (which I assume are the wholesale energy-only part of the bill [1]) of $.009-$.01/kWh [2], and, IIUC, wholesale electricity is about 4x that.
This is to say that an efficient enough electric heat pump (which I believe is plausible for whole-house heating, not high-temperature use cases like a dryer) could at least get close to gas in operating cost.
[1] only about 1/7th of the retail total, something which would likely surprise most consumers. This seems true for electricity, too, where, IIRC, the energy costs $.04/kWh, but PG&E charges upward of $.24/kWh at the highest residential "tier".
[2] converted from $/therm using 29.300111111111 kWh/therm
