How many watts does a heat pump use?
A heat pump uses 1,780–3,820 watts while running, which is 7.4–15.9 amps at 240 V.
Heat pump watts, amps and circuit
| Running watts | 1,780–3,820 W |
|---|---|
| Voltage | 240 V |
| Running amps | 7.4–15.9 A |
| Circuit | dedicated 240 V circuit, breaker size from the nameplate |
Also called: air source heat pump, 3 ton heat pump.
Heat pump watts by size and type
| Size or type | Running watts, W | Volts, V | Amps, A | Starting watts, W |
|---|---|---|---|---|
| Heat pump | 1,780–3,820 | 240 | 7.4–15.9 | — |
| 2 ton | 1,780–1,900 | 240 | 7.4–7.9 | — |
| 3 ton | 2,730–2,890 | 240 | 11.4–12 | — |
| 4 ton | 3,500–3,820 | 240 | 14.6–15.9 | — |
| Backup electric heat strips | 4,750–15,000 | 240 | 19.8–62.5 | — |
What size generator runs a heat pump?
A heat pump needs a generator that supplies at least 3,820 running watts. Starting a heat pump takes a short surge of several times its running watts, and the surge is not listed here: size the generator from the locked-rotor amps (LRA) on the nameplate or the maker's generator guidance, not from the running watts. The generator must have a 240 V outlet or be connected through a transfer switch or interlock.
What it costs to run a heat pump
Running a heat pump at 2,800 W, the middle of its 1,780–3,820 W range, for one hour a day uses 1,022 kWh a year. That costs about $184 a year at $0.18 per kWh, the US average residential price for August 2026.
Your bill's total ÷ kWh used. 0.18 is the US residential average.
- Per day
- $0.50
- Per year
- $184
- Energy per day
- 2.8 kWh
- Energy per month
- 85.2 kWh
How it is calculated
- kWh per day = 2,800 W × 1 h ÷ 1,000 = 2.8
- Per month = 2.8 kWh × 30.4 days × $0.18 = $15
What affects heat pump power use
The running watts are the total system power in cooling at 95 °F outdoors from the makers' performance tables. A heat pump moves heat instead of making it, so its compressor draws far less than electric resistance heat for the same warmth. In very cold weather the backup heat strips in the air handler switch on and draw much more; they are wired on their own circuit. The outdoor unit breaker comes from its nameplate.
How the amps are calculated
Amps = watts ÷ volts. For 3,820 W at 240 V that is 15.9 A. The 1,780–3,820 W range covers typical models; the nameplate on a heat pump gives the exact figure.