My father has a Mitsubishi air-water heat pump, generating hot water for the iron radiators in the house. Uses R32 refrigerant, not CO2 as in this article, but

My father has a Mitsubishi air-water heat pump, generating hot water for the iron radiators in the house. Uses R32 refrigerant, not CO2 as in this article, but still. While efficiency is reduced by the need to have decently high temperatures in the radiators, it's still decent-ish. IIRC he still gets a COP of around 2-2.5 when it's -15C outside. This is in Europe, might be different on the other side of the pond.