Hi all! I know in previous posts i was not optimistic about cold weather heating with this 12kbtu heat pump.
After using it hard for a month i gotta say it works great! The heat pump has maintained the garage at 40°-52°F (8°C) during 7°-20° (-10C) outside temps with heavy cloud cover and running continuously. Tstat set @80F. Current is right at 5A 243V. Defrosting every 40 to 120 minutes. Attached is a photo of the ice it has melted from the coils lately, 92% humidity last night. Id say more than 5 gal ice there.
A 1200W electric heater produces about 4100 btu/hr. Im fairly sure its outputting twice that judging by garage temp. I shut it off for now and turned on a 5400 btu unvented propane burner so will see what happens to the garage temperature. The doors have been used very little, maybe once/day so will be fairly good comparison.
All in all its a win for heating with electricity. With mild outdoor temps, the cost per btu is very close to propane, maybe cheaper in some cases. As hard as the poor thing works to heat i would think longevity may not be that great but who knows. So far so good.
(Update)
After running the propane 5400btu heater last night instead of heat pump, the garage temperature dip at night was 5 degrees, very similar to the heat pump so that means under 10°F (-12°C) outdoor conditions we arent doing a lot more than resistance heating, maybe x 1.3 at best. Why this is important? Well, in those conditions, why wear it out when theres no gain? Use a simple resistive heater or propane in those conditions. So my (at a glance) conclusion is... A 19 SEER 9.5HSPF air source heat pump will do you well as a heater from 25•F.
(-4°C) on up and i expect cooling will be fantastic. Happy New Year!