The HP is 16 SEER and the furnace is 87% as its oil and not propane. I have propane in another house and I like it better and only if you own your own tank. But this house was setup for oil with the oil tank already in the basement etc., so I just went with oil again.
I did not go crazy with a high Seer on the HP because I did the math and this place is tops on energy efficiency and there would be no payback
I'm thinking to add a heat exchanger myself.
How much heating power does yours have, and what's the efficiency?
Didn't think you could use them at those temperatures, figured the evaporator would be solid ice. Good news I suppose, but how hot can you get the water at those temperatures?