Air source heat pumps don't cost significantly differently from gas furnaces or boilers, especially once you account for running costs. Anyone with A/C already

Air source heat pumps don't cost significantly differently from gas furnaces or boilers, especially once you account for running costs. Anyone with A/C already has an air source heat pump, just one that only moves heat from inside the house to outside. Moving heat in both directions take some extra valves and an extra heat exchanger, but this doesn't dramatically increase costs. The basic principal and components are exactly the same. Ground source is expensive, but that's due to drilling and/or trenching. The actual heat pump is a tiny fraction of the bill to install ground source heating.