How Heat Pumps Work and How Much You Save on Heating
Put your hand near the back of your refrigerator. Feel that warmth? That’s heat the machine pulled out of your groceries and dumped into the kitchen. Now scale that cycle up, flip it so the warm side faces your living room, and you understand how heat pumps work — because that’s genuinely all it is. A closed refrigerant cycle pulls heat from the outside air and moves it into your home, with electricity paying only to run the compressor. That’s why efficiencies climb above 300%, and why the savings hit hardest for anyone leaving electric resistance or oil heat behind.
The rest of the story — costs, sizing, incentives — lives in the complete heat pump guide.
The cycle in 4 stages
The refrigerant makes an endless loop with four stops along the way:
- Evaporation: the refrigerant absorbs heat from the outside air and evaporates.
- Compression: an inverter compressor raises its pressure and temperature.
- Condensation: it releases that heat to your home’s air or water.
- Expansion: a valve drops the pressure and the cycle restarts.
Only the compressor draws real power; the heat itself is free for the taking. That’s how the system delivers 3 to 4 units of heat per unit of electricity — arithmetic that electric baseboard heat can never match, because resistance heating gives you exactly 1 for 1, no matter how much you spend on it.
How much you save
The savings math depends on your local electricity, gas and oil prices, but the physics tilts the field: a heat pump typically cuts heating energy use by 40–60% versus combustion, and even more versus electric resistance. And because the same machine reverses in summer, it replaces your air conditioner too — so the savings don’t take the season off.
To see why, compare what each system gives back for what it takes in:
| System | Efficiency | Also cools? |
|---|---|---|
| Heat pump | 300–400%+ | Yes |
| Gas furnace | 90–98% AFUE | No |
| Electric baseboard | 100% (COP 1) | No |
The furnace is bumping against a hard ceiling — you can’t burn fuel at more than 100% — while the heat pump plays a different game entirely.
One habit quietly ruins these numbers, and service techs see it in house after house: running a heat pump like a furnace, cranking it on and off. A heat pump would rather hold a steady temperature with long, low runs; constant on-off cycling is exactly the pattern it’s worst at.
For the head-to-head on running costs, see the full heat pump vs gas furnace comparison.
Frequently asked questions
Why does it use less than electric baseboard heat?
Baseboard heat converts 1 kWh of electricity into 1 kWh of heat — that’s its ceiling, by physics. A heat pump uses that same 1 kWh to move heat from the outside air, delivering 3–4 kWh into your home. You’re paying for transport, not manufacture.
What is the heating curve / weather compensation?
It’s the control logic that adjusts the water or air temperature based on what’s happening outdoors — milder day, gentler output. The payoff is efficiency: the system never works harder than the weather requires.
Does the defrost cycle use much energy?
It nudges consumption up on cold, humid days, but it’s brief — and it’s what keeps the outdoor coil clear so the unit stays efficient. Think of it as the machine sharpening its own tools.
Does it save in summer too?
Yes. The same cycle in reverse cools more efficiently and more evenly than a standard air conditioner, so the machine keeps earning its keep after the heating season ends.