Yeah we have a heat pump too but it doesn’t cut it at these temps. The system automatically switches to propane below 10 degrees or so. Aside from the efficiency issues, you also get ice outs on the heat pump in the winter which can be a problem so a backup is always necessary. But the fireplace is awesome! It has a fresh air intake from the outside and a catalytic combustor, the thing gets HOT! Plus it has a fan that brings the heat downstairs. I discovered too late that it could be tied into the hvac system to distribute the hot air throughout the house, but it works great as it is.