> air source heat pumps have been getting a lot better
Mitsubishi, specifically, makes a heat pump with the marketing vernacular, "H2i" or "hyper heat" which has reasonable efficiency down to -13F/-25C.
Mitsubishi, specifically, makes a heat pump with the marketing vernacular, "H2i" or "hyper heat" which has reasonable efficiency down to -13F/-25C.
My mini-split system worked fine down to about 10F, then it was defrosting for 10 minutes after every 8 minutes of use or so. I just turned on crypto miners on a few computers to supplement. Laptop crypto mining is useful if you want to keep your hands and wrists warm, hats, blankets, sweaters, and some old 100+ watt light bulbs will also help.
All this is to say "you can just get a -30 degree capable system" is out of reach for most people in the world. A large swath of people geographically close to my house still use window or wall HVAC units, rather than ducted systems. I was the only split ductless system my HVAC installer had ever installed - they had to come fix their install 4 times (four!) and eventually i contacted the asurion purchase protection people and got refunded for the cost of the HVAC system.
it works fine now, i told the HVAC installer to cut the threaded connectors off everything and sweat all the copper lines together, and it hasn't had an issue since.
it was always breaking in the late fall and early spring, where it had to heat at night but cool during the day, it would always break around 11AM. The pressure differentials must have been an afterthought in the design, i guess.
the system i have now is also a minisplit, but it has 5 heads, and is 5.5 tons. If i run one of 4 heads by itself, it can do 3 tons to just that head. the fifth head is smaller BTU, i think it's 3/4 ton max. It cost $3,723.68, plus an additional $5000 to get it installed and working, give or take. As i mentioned, i got the $3723 refunded due to manufacturer's defect.