When I talk to people about air-source heat pumps, their general impression is of the old freon charged units popular for awhile in more temperate climates.  Last summer we installed an R410A charged mini-split air-source heat pump to heat the central zone of the house.  It has been running pretty much non-stop since mid-October, and last night when it hit zero was no exception.  That zone on the oil heating system is set at 68 and has yet to go on this winter.  Where the unit was using about 10 Kwh/day in November ($1.50), it used 24 in the last 24 hours ($3.72).  That’s about what a gallon of oil costs.  With the woodstove covering the other major zone since December, we’re currently at about 50 gallons of oil and about $186 worth of extra electricity for the season.  Last winter we burned 500 gallons of oil in addition to wood.

Data recorders are keeping all the data, and I’ll have an accounting of the winter experience in the Spring.