[Reason077]

> ”Are you looking a at a heat pump heater? If so, how much of its energy would be pulling heat from the house that needs to be replaced by the home's heating supply anyway?”

Heat pump water heaters pull heat from the outside. Usually with a split outdoor unit, just like normal A/C and heat pump systems.

I’ve also seen models where the entire system (integrated storage cylinder for the heated water) is installed outdoors, but those are presumably meant for more mild climates.

In any case, they certainly don’t pull heat from inside the house.

[Marsymars]

Thanks, that obviously makes more sense. (I think I was thinking about heat pump clothes dryers at the same time I was making that comment.)

[Reason077]

Heat pump dryers don’t cool the room either because they work in a closed loop. There’s no external vent removing hot air to the outside like a conventional dryer. So they pull heat from the room but also put it back in the room, and the overall effect is to warm up the room slightly.