What size generator to run a furnace blower fan?
Furnace blower fan sizing at a glance: it draws 600 running watts, surging to 1560W at startup.
| Spec | Value |
|---|---|
| Running watts | 600W |
| Starting (surge) watts | 1560W |
| Recommended class (this load + margin) | 2000W |
Why the startup surge matters
Because a furnace blower fan has a motor, it surges to about 1560W at startup — roughly 2.6× its running draw. If you size a generator only for the running watts, it can stall the instant the furnace blower fan switches on. Always size for the surge.
Sizing the whole system
The number above covers the furnace blower fan 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 furnace blower fan use?
A typical furnace blower fan draws about 600 running watts, but needs roughly 1560 watts at startup due to motor surge.
What size generator runs a furnace blower fan?
For the furnace blower fan alone plus a safety margin, a 2000W (≈2.0kW) class generator is appropriate. Add your other essential loads to size the full system.