As if anyone really cares, I actually checked out my numbers on the heat pump. It turns out that at full tilt boogie, the compressor, fan, and water pump pull 2.9kW. This lowers the cost-per-hour to $0.1531, making it an incredible cost savings over gas. In cold weather, most heat pumps switch over to electrical resistance heat. An equivalent amount of resistance heat to our 3-ton heatpump is 10.5kW meaning a cost of $0.5544/hr. Most folks without gas end up in this situation. Why don’t we? Our heat pump is ground-coupled, also called geothermal or ground-source. What we have is a 1200′ loop of pipe buried 6′ down that we circulate water through. At 6′ down, the temperature is near 60F year round. Instead of trying to extract heat from cold outside air in the winter, we can pull heat out of the ground all day long. In fact, most heat pumps will quit working and switch to electrical heat in cold weather simply because the outside unit will move its heat into your house, condense water, freeze it and promptly quit working. We have a similar advantage for summer cooling – we can pump heat into the dirt instead of trying to get rid of it in 90F air. And there’s no ugly box outside the house.

We’ve told people building new houses that they should consider ground-source. So far, they haven’t. They also have higher utility bills.