Ask for the capacity at the low end, not just at rest
Every heat pump has a rating for how much heat it can still pull from outside air as the temperature drops. Some units fall off fast and lean hard on backup heat once it gets cold. Others hold most of their output much further down. Ask for that number at a low outdoor temperature, not just the standard rating, because that's what tells you how the system behaves on the coldest nights, not just the mild ones.







