On: The Cuboid: A DIY air purifier that's better than a box-fan (2021)

[turtlebits]

The only problem is that instead of re-circulating and filtering conditioned air, a furnace fan is going to bring in external unconditioned air (and is only filtered once).

[willcipriano → turtlebits]

Your furnace pulls from outside? Mine doesn't. I would've thought you'd want to heat the warmer indoor air to save energy.

[Waterluvian → turtlebits]

I haven’t had a central air system that does this. Mine have always had return vents and it just cycles internal air.

I’m actually very curious about more intelligent systems. Those that can:

- bring in outside air on occasion to freshen things up

- negotiate the best way to cool a home depending on outside air. It drives me mad when my AC kicks on and it’s actually colder outside.

[dzhiurgis → Waterluvian]

> - bring in outside air on occasion to freshen things up

All HRV's do that. "single room recuperator" from aliexpress is in every flat after renovation in Lithuania.

[the_sleaze9 → Waterluvian]

As a kid I always wanted an external vent on the refrigerator that pulled in outside air when it was cold enough.

[nomel → turtlebits]

I’ve never seen a furnace fan that pulls in outside air, unless it was some DIY garbage that wasn’t to code, or a huge money waster from 100 years ago.

[afterburner → turtlebits]

An office or school's central air system might bring in some outside air, but regular house systems don't. They have intake grills inside the house.

[kshahkshah → turtlebits]

From where? Bringing in outside air is what a 'fresh air' system does like an ERV or HRV

[SkyPuncher → kshahkshah]

Most older homes simple have an outdoor draft/damper for makeup air.

You’ll draw in a lot of dirty outside air with that setup if you don’t block/reduce outside air intake. It will still go through a filter, but it’s going to cause the filter to dirty very quickly.