Doesn’t geothermal have to use an electric back-up heater because it can’t keep up with cold weather?
Geothermal systems are designed case by case. Diminishing returns often suggest that we employ auxiliary heat vs., trying to do everything with the heat pump. I don’t have to tell any one in Michigan in 2009 that occasionally we get down to temperatures in the negative teens, these occasions are much less expensive to handle with auxiliary electric coils or other back up heat sources.
