You're about 20 years behind.

My heat pump is working great at 0F. It's 7 years old.

jcgrillo 41 minutes ago | parent | next [-]

Mine are in climate zone 6. They're only a couple years old. The coldest temperatures I've run them at so far are -21°F and they kept the house adequately unfrozen. They'll maintain a COP of 2 down to 5°F IIRC. The hot water heater is an 80gal Rheem heat pump unit. No complaints there either. It would be pretty great to have some thermal storage though, temperatures in the dead of winter here are usually above 5°F during the day but drop well below zero at night. Blasting the heat pumps during the day to bank heat for overnight would be far more efficient.

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baggachipz 8 hours ago | parent | prev [-]

heat pump for house !== heat pump for hot water

	▲	Youden 8 hours ago \| parent \| next [-]
		I don't know what it's like where you're living but here in Switzerland it's completely normal to have one heat pump that does both. Here there's a lot of floor heating, which also uses water, so you usually just run one loop to the "boiler" (a water tank with a copper loop for the water from the heat pump to circulate through) and one through the floor and have a valve to switch which is running through the heat pump. I have one of these: https://cta.ch/en/private/products/ah-i-eco-innen I got it in October so most of the time I've had it has been <10C. It's produced 806.3 kWh of heating for hot water and 6587.2 kWh for the floor heating. It consumed 302.7 kWh and 1801.4 kWh respectively, for a COP of 2.66 and 3.66.
	▲	serpix an hour ago \| parent \| prev \| next [-]
		Yes, same thing. Heat pump to heat exchanger. This is over 39 years old tech and in common use around Scandinavia and mainland europe. This is ancient technology.
	▲	gwbas1c 7 hours ago \| parent \| prev \| next [-]
		There's a lot of different heating systems: If your heating system uses hot water at any point, (baseboards, hydro-air, underfloor, ect,) using a single heat pump makes a LOT of sense. Personally, I prefer an air-source heat pump hot water tank. It significantly dehumidifies my basement.
	▲	karussell 8 hours ago \| parent \| prev [-]
		Why not?