Air source heat pumps are cost effective if you live in the correct location, and depending on your electric and primary heat source rates. Basically, the cost of electricity to run the thing has to be less than the cost of the fuel you use to heat your house; oil or gas for most Americans. The other thing to think about is that the heat pump has its own efficiency range; providing heat is less efficient below 40F, and cooling works best below 100F. Within their operating temperatures for heating and cooling, they are more efficient than electric heat since electric heat directly converts the electricity into heat as opposed to just moving it inside from outside.
So in my house, we use an oil furnace for heat, and oil is not as cheap as natural gas these days. There are no gas lines near my home, so we decided to look for another alternative. The cost of oil for my house and the electric rates in my area is high. The heat pumps, we purchased 2 for our home, one 3 years ago, and the second 2 years ago. We run the heat pumps to warm our home every day the temperature is above 40F, or so, and of course we use it for cooling when it’s hot out.
We end up using them for heating in October and November, and then again in March and April. Some days in January and February, are warm enough in the NY area to make it cost effective. We found for our home, we have saved about 500 gallons of oil each year for the last 2 years. Granted there are some assumptions here, as no two years are the same, but our average went down that much. I’ll keep updating this in the future.
While oil, like everything else, is expensive here compared to other parts of the country, so is the installation of these systems. This basically makes the breakeven date about 10 years, less if you compare the cost of cooling with these things over window or wall AC units. I can do that since our house had them when we bought it, and these units are whisper quiet in operation, particularly as compared to window/wall A/C units.
They seem to be becoming more common these days, and for homes like ours built without central air ducting, they are superior to my cooling alternatives.