I should start by saying that my house faces southwest and during the winter when the sun is low in the sky and hits the cathedral windows almost all day I don’t need much heat. Two to three hours of sun this morning was enough to heat the place to 65 with an outdoor temperature of 31. The afternoon brought snow flurries and temps in the high 20’s; the central forced air heat only went on an hour ago. In the summer when the sun is higher it hits the roof, not the windows, and with cross ventilation on two floors and the top floor a loft my need for AC is minimal. September and October are the only two months that bring days when the little window unit that came with the place is inadequate.
I had a need to back up the central heat so my reptiles in the finished out basement wouldn’t freeze if it went out while I was traveling in winter. A contractor suggested heat pumps. They may end being just the ticket for cooling in early fall but they chew as heaters. The lowest temperature setting is 62; some sort of design limitation. That’s warmer than I want things and well above hibernation temperatures for the critters. Worse still, the heat pumps stop working and the heaters switch to operating on electric strips when the outside temperature approaches freezing - which is the only time I need any significant heat. In summary they go on when I don’t need them to and when I do need them they stop being heat pumps and become energy gobbling box heaters. At least they are small and unobtrusive. But they will never be switched on in winter unless I’m away.