We have a heat pump water heater. There is a compressor with a phase-change fluid on top of an 80-gallon tank. It extracts energy from the air in the basement to heat our domestic water. It works great and only uses about 1 kilowatt-hour per day (1/3 of the energy that our old electric water heater used.)
The efficiency of the heater is a function of the air temperature around it. We’re both energy geeks (if you hadn’t figured it out yet) so we’re always looking ways to squeeze out a little more performance from our gizmos. Recently Li Ling has started to pull the dryer vent off the wall to vent the warm exhaust directly into the basement.
This is quintessential “energy freakshow” material.
Energy Freak Show 
We tried blowing dryer exhaust into the house to save heat. It slowly turned into a dust disaster. Even though a screen catches the lint, the finer dust blows through getting in and on everything. I’ve never seen a heat pump water heater before. Interesting.
By: Paul Butler on October 12, 2012
at 10:48 am