Feel free to skip the long preamble and go straight to the question.
My vacation place has a heat pump, in addition to my undersized insert. I keep it at 42' when I'm not there. It usually doesn't have too hard a time keeping it at that temp, and I disabled the strip/aux heat. When I go there, if I'm getting there at night the stove won't be able to bring the house up to temp before bedtime. So I remotely turn up the HP to 55-60'. Since I don't care how long it takes to get up to temp (I can turn up the heat in the AM), I don't need the aux heat. Last year however, we had a particularly long cold snap; single/some neg numbers at night, teens during the day for >1 wk. The HP was barely able to keep the place above freezing, and the compressor was running non-stop. I got a huge bill.
SO...
At what point is the efficiency of the compressor offset by extended run times? Or I guess, how many hours of compressor time = 1 hour strip time? Obviously that depends on the HEER of the unit (which I don't know ATM) and the power of the strips (which I have no idea about). And the outside temps I suppose. Hmm, this is becoming complicated.
My vacation place has a heat pump, in addition to my undersized insert. I keep it at 42' when I'm not there. It usually doesn't have too hard a time keeping it at that temp, and I disabled the strip/aux heat. When I go there, if I'm getting there at night the stove won't be able to bring the house up to temp before bedtime. So I remotely turn up the HP to 55-60'. Since I don't care how long it takes to get up to temp (I can turn up the heat in the AM), I don't need the aux heat. Last year however, we had a particularly long cold snap; single/some neg numbers at night, teens during the day for >1 wk. The HP was barely able to keep the place above freezing, and the compressor was running non-stop. I got a huge bill.
SO...
At what point is the efficiency of the compressor offset by extended run times? Or I guess, how many hours of compressor time = 1 hour strip time? Obviously that depends on the HEER of the unit (which I don't know ATM) and the power of the strips (which I have no idea about). And the outside temps I suppose. Hmm, this is becoming complicated.