I hear from a lot of people that heat pumps are don't work in cold climates. This one that we just installed (Bosch's IDS Ultra) has a boosted compressor. It can provide heating at 100% capacity down to 5°F. What happens if the temperature drops below 5°? The unit will continue to initiate heating even down to -13°F. The colder it is outside, the more difficult it is to extract heat from the outside air. The boosted compressor “borrows” additional heat from the hot side of the refrigerant cycle