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What type of heat pump do you have? I have a ducted split system with a HSPF of 9.5, and I'm actually pretty disappointed with how it performs. In our new-ish, better-than-average insulated house, we've had some insane electrical bills over the last couple winters compared to the gas bills we had in previous years (prior to renovating).

Sometimes I wonder if the installer didn't really know what he was doing.

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What heating elements or output temperature are you runnng your HP at, and do you have buffer storage or not?

It's an air-air ducted system. I live in the North East US, so winters are generally cold, with a few days around 0F/-17C. During heating season we keep it at 67F/19C.

That's a COP of 2.8. You have to check the efficiency graph and your mean winter temperatures, because I suspect it operates fully resistive at below -10°C or so. I also noted underwhelming performance and increased faulty compressor incidence for air source heat pumps with the external unit mounted on Northern walls (in the Northern hemisphere). I suspect it doesn't get sunshine and the defreezing resistive element is operating a lot, driving up energy costs.

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