[masterj]

I love heat pumps, but the author should have had an energy audit done first. Likely a thermal camera on a cold day would quickly identify their envelope issues.

> one from the clothes dryer (when I hold an incense stick up to it I can see it pulling in air even when it’s not running)

A normal vented clothes dryer can vent something like 8000 cu ft of air in a normal drying cycle (i.e. all of the air in their apartment). If that's running all the time somehow, that could definitely explain a lot. If that's the case they should fix it, and maybe explore ventless heatpump dryers.

[namibj]

Doesn't need to be a heatpump dryer, just needs to be ventless.

E.g. the 20+ year old common German dryer that runs the clothes air closed-loop, first through the clothes, then to a heat exchanger with drainage geometry (typically feeding into a tray you have to pull out and pour out after each cycle), then across an electric heater, circulation fan, and back to the clothes. A second fan blows room air across the heat exchanger; the dryer action relies on the clothes being much warmer than room temperature such that the desired relative humidity of/at the clothes doesn't survive the cold from the room temperature.

[masterj]

Yeah, modern heat pump dryers are just nice and have cycle times more in line with North American expectations, but you’re right that alternatives have been around a long time!