bbbbbThe Mitsubishi Hyper heat can work down to -13F,
The absolutely best resource I’ve found for heat pump research is the NEEP database which will you give you actual BTU outputs at various ambient temperature readings: ashp.neep.org/#!/product_list/
Also worth considering a geothermal heat pump depending on your geography, as then you have a guarantee of efficiency all year round
Thanks for the website!
Second the NEEP database. I’d just add that the lowest temps listed here aren’t the actual equipment minimums - each model has a cutoff temp where it will literally shit the bed (except ground source of course). For my mistu hyper heat, it’s -26F. Capacity will keep dropping after -13F though (where it’s still at like 80% I think).