Lots of good info here, but some seriously out of date, and incorrect, info as well.
The good (info): Yes, pay attention to COP on any system you are considering, and comparing kWH (electrical service) costs against BTUHs (gas/propane) is always a wise move. But more importantly: Run the numbers and do the math! You're going to be living with the with this equipment for 15-20 years, so you need to make the right move for you. Does the math work? Does this make sense?
Again: Run the damn numbers! If you don't know how, or where to get started, contact your utility company, as they will no doubt have calculators, or links to non-partisan sites that can help you. DO NOT RELY ON A SALESPERSON FOR THIS!
Second, the rebates are just that: Rebates. They're not political, they're nothing to get nervous or paranoid about, and Big Brother isn't doing this to try to "control" or "manipulate" you. Leave that paranoid **** to the politcos and move on.
The bad (info): Current air source heatpumps are orders of magnitude better than they were as recently as 10-15 years ago, so pay no attention to the "no good below (a certain temp)" BS. Yes, you will need back-up/"emergency" heat of some sort with an air source HP, but....
There's a term called a "balance point", and it's simply the OA temperature at which a system will need to switch from HP operation to back-up/"emergency" heat for "comfort heating", and this temperature will differ for every building and configuration. On older, less efficient systems this temperature was often as high as 25-30* F, but some currently offered high efficiency HP systems can generate usable heat as low as 0* F (and minisplits can go to -22* F and even lower). Exactly how this occurs would take-up too much time and space to explain here, but if you can wrap your head around the ideas of -30* dewpoints, or boiling temps of -40*, that's a good start.
Regardless, if you go the HP route your balance point will be based on the construction of your home, the efficiency of the system you purchase, and perhaps most importantly, your own comfort. Also, it's a calculated value, and while it's a good starting point, it's not carved in stone and can be changed, as what works for others may not work for you.
In my opinion: Contact your utility provider, run the numbers, and get the most energy efficient system you can comfortably afford.
Jim
