How many watts does a furnace blower use?
Every number here comes from a named source. Generator charts give a generous figure for sizing a generator or power station. Test data and manufacturer specs show what the appliance draws.
- Running
- 100 to 700 W
- Extra at startup
- 1,400 W
- Voltage
- 120 V
How long it runs on a battery
| Battery | Runtime |
|---|---|
| 1 kWh | 1.7 h |
| 2 kWh | 3.4 h |
| 3 kWh | 5.1 h |
| 5 kWh | 8.5 h |
Running nonstop at 500 W, with 85% of the battery usable after inverter losses.
What each source says
| Figure | Value | Source and basis |
|---|---|---|
| Running | 500 W | Scott Pigg, The Electric Side of Gas Furnaces, Home EnergyField study of 31 new Wisconsin furnaces (2002): furnaces with standard PSC blower motors averaged about 500 W. |
| Running | 100 W | Scott Pigg, The Electric Side of Gas Furnaces, Home EnergySame study: furnaces with ECM blower motors averaged about 100 W in fan-only mode. |
| Standby | 8 (up to 12) W | Scott Pigg, The Electric Side of Gas Furnaces, Home EnergySame study: 8 W standby for PSC furnaces, 12 W for ECM furnaces. |
| Running | 700 W | EWEB, Generator Sizing ConsiderationsGenerator sizing chart, 1/3 hp furnace fan blower. |
| Extra at startup | 1,400 W | EWEB, Generator Sizing ConsiderationsGenerator sizing chart, 1/3 hp furnace fan blower. |
Good to know
- A gas furnace needs electricity for its blower, combustion fan and igniter, so it won't heat during an outage without backup power.
- Furnaces built since July 2019 must meet DOE fan efficiency rules, which pushed makers toward ECM motors.