@crispius I’ve had a heat-pump water heater in my unfinished basement for the last 3 years or so. No one lives in our basement, so not quite the same situation as yours. I’m guessing your basement is finished? If so, and you end putting the HPWH in a separate room, I don’t think you’ll notice any temp difference at all. Ours doesn’t actually run that often, so it’s not always blowing cool air into the space. And in the summer, it would be a bonus.