Tip
How heat pumps actually work
A heat pump is the same hardware as an air conditioner — refrigerant, compressor, evaporator, condenser — but with a reversing valve that lets it run the cycle backward. In summer it pulls heat from inside and dumps it outside (cooling). In winter it pulls heat from outside and dumps it inside (heating).
"How can it heat when it's cold outside?"
This is the most common question. Answer: even at 10°F outside, there's still significant heat energy in the air; the heat pump's refrigerant cycle moves it indoors. Modern cold-climate heat pumps maintain rated capacity down to about 5°F (some down to -15°F). Below that, electric resistance backup heat fills the gap.
Efficiency: COP and HSPF
- COP (Coefficient of Performance): heat output ÷ electric input. A heat pump with COP 3 produces 3 units of heat for every 1 unit of electricity. (For comparison: electric resistance has COP 1.0; gas furnace has efficiency 0.92-0.97.)
- HSPF2 (Heating Seasonal Performance Factor): averages COP across the heating season. Modern heat pumps run HSPF2 8.0-10.5.
Why it's the IRA's biggest rebate stack
| Program | Heat pump rebate |
|---|---|
| IRA 25C federal credit | $2,000 |
| DOE HEAR (income-eligible) | $8,000 |
| DOE HOMES (performance) | $2,000-$8,000 |
| Typical utility rebate | $500-$3,000 |
| Typical state program (Tier A states) | $1,000-$5,000 |
| Total possible stack | $8,000-$14,000+ |
When heat pumps DON'T make sense
- You have very cheap natural gas and very expensive electricity (math may favor staying on gas)
- Your home is severely under-insulated (heat pump load exceeds capacity)
- You don't qualify for HEAR and don't have utility rebates (federal credit alone may not justify replacement of a working furnace)