> That's great for the warmer side of the state but most heat pumps don't work great when it's 10 below - they approach zero efficiency the colder it gets.
Mitsubishi heat pumps with the "Hyper-heating inverter" technology are above 100% efficiency down to -15℉ (-26℃). They are 200% at 0℉ (-18℃), 300% at 32℉ (0℃).
Their capacity drops from 100% at 23℉ (-5℃) to 76% at -13℉ (-25℃).
Fujitsu has similar technology, as do a few others now.
Mitsubishi heat pumps with the "Hyper-heating inverter" technology are above 100% efficiency down to -15℉ (-26℃). They are 200% at 0℉ (-18℃), 300% at 32℉ (0℃).
Their capacity drops from 100% at 23℉ (-5℃) to 76% at -13℉ (-25℃).
Fujitsu has similar technology, as do a few others now.