Is a heat pump worth it? Online calculators are a hugely mixed bag with obvious biases on many of them, and installers all want to sell their favorite gizmos so it's hard to get a straight answer from them.
Our current details:
forced air propane furnace and water heater, both getting close to the end of their useful life. The furnace is 80% efficiency, and I have no idea about the water heater, though given the choices made in this house, I expect it's roughly the same. It's a 50 or 60 gallon unit.
We pay an average of $0.10 per kWh for electricity. We pay $2.30 per gallon for propane.
roughly 1700 sq ft, two stories, but one end of the house is a two-story space. Build in roughly 2001, so reasonably insulated.
This is us, in degrees F (avg high temp, avg low temp, avg temp):
January | 45.3| 34.8| 40.0
February | 48.5| 35.6| 42.0
March | 52.6| 37.6| 45.1
April | 57.1| 40.2| 48.6
May | 62.6| 44.8| 53.7
June | 66.5| 48.3| 57.4
July | 70.8| 50.7| 60.7
August | 71.9| 51.0| 61.4
September | 67.3| 46.9| 57.1
October | 58.2| 42.1| 50.2
November | 49.8| 38.1| 43.9
December | 45.0| 35.0| 40.0
I would say in each of the four winter months there's a period of a few days where it's really cold. It's very unusual to have a prolonged cold snap, but it can happen. "Cold snap" around here is 25F for a few days.
The local energy company will give us a $1,500 credit to switch from forced air propane to any type of heat pump.
The furnace comes on intermittently in October, is regularly on in Nov - March, and is usually off again by early May. We keep the house around 67 during the day and 64 at night.
There are maybe a few weeks over the summer when some cooling would be nice, but it's not necessary.
I don't mind paying a bit more for a system, but cannot afford to spend, say 4x for a heat pump if it's not going to save us a lot over time. I'm confident a ground-loop system is well-outside our price range. We have ducting throughout the house so would prefer to re-use that for delivery of heat.
I mention the water heater as I don't mind it staying propane, but would have no objection to using the heat pump + electric or solely electric for that. We do keep the water fairly toasty, maybe 130 degrees, we never run short with our current tank, there are two of us here.
Those two energy choices are what we have available; natural gas is not around, solar is too expensive (but would be compatible with the heat pump, I guess, in the future if we somehow did that), and we do not have a wood source of heat and really don't want one. Environmental impact is something I like to think about but budget will intrude on anything grandiose.
Many thanks for any insight.