What size generator to run a heat pump (3-ton)?
Heat pump (3-ton) sizing at a glance: it draws 4000 running watts, surging to 14400W at startup.
| Spec | Value |
|---|---|
| Running watts | 4000W |
| Starting (surge) watts | 14400W |
| Recommended class (this load + margin) | 17500W |
Why the startup surge matters
Because a heat pump (3-ton) has a motor, it surges to about 14400W at startup — roughly 3.6× its running draw. If you size a generator only for the running watts, it can stall the instant the heat pump (3-ton) switches on. Always size for the surge.
Sizing the whole system
The number above covers the heat pump (3-ton) on its own with a safety margin. In a real outage you'll run other things too — and the right method is your total running load plus the single largest surge among everything, not the sum of every surge. Use the full calculator to size your actual setup:
Common questions
How many watts does a heat pump (3-ton) use?
A typical heat pump (3-ton) draws about 4000 running watts, but needs roughly 14400 watts at startup due to motor surge.
What size generator runs a heat pump (3-ton)?
For the heat pump (3-ton) alone plus a safety margin, a 17500W (≈17.5kW) class generator is appropriate. Add your other essential loads to size the full system.