Neighbor has a heat pump. It's good till late September early October depending on the temp. It's a pretty big house. I think it has a natural gas furnace. Our fin tube baseboards and a few cast iron radiators work down to the single digits and then the blower part of the system kicks in. It get's it's heat from the same boiler through a big radiator/coil and a huge squirrel cage fan. That fan is also part of the central a/c with 2 flat condensers in the air handler.
