Comment by wffurr
You already dump waste hot air into your kitchen from the refrigerator during the summer. Is this much different?
It does seem a little silly to have these chains of heat pumps all working in various directions. I read about "cold district heat" in a sibling comment which circulated lukewarm water to use as a heat sink or source with heat pumps. Maybe something similar could be done with a water or refrigerant loop through the house. Probably not economical to do all the plumbing though.
> you already dump waste hot air into your kitchen from the refrigerator during the summer. Is this much different?
Heating water is very energy intensive, fridges are a rounding error compared to water heaters