A gas furnace's blower motor typically uses about 500 watts, ranging from roughly 150 W for an efficient ECM motor at low speed to about 1,000 W for a large older PSC motor. Allow about 1,400 watts to start it.
- Running watts
- 500 WTypical; 150–1,000 W across models
- Starting watts
- 1,400 WPSC blower motors surge briefly at start; ECM (variable-speed)…
- Per day
- 4.2 kWh24 h of use, cycling
- Current
- 4.2 AAt 120 V while running
Figures checked against DOE, ENERGY STAR and manufacturer data on . Your model's label is the final word.
Watts by model and setting
Most furnace blower models draw between 150 and 1,000 W while running; a typical one draws about 500 W. Assumes a 500 W blower running about 35% of a winter day. DOE-cited figures put furnace fans near 1,000 kWh a year in a typical home.
- Motor size (1/4 to 3/4 hp or more) and speed setting
- Motor type: ECM blowers use much less power than PSC motors, especially in continuous fan mode; DOE fan standards since July 2019 pushed new furnaces to ECMs
- Duct static pressure and dirty filters make the blower work harder
- Running the fan continuously ('On') instead of 'Auto' increases daily use
- The igniter, inducer fan and control board add a smaller load during each heating cycle
Running a furnace blower on a generator or power station
- Generator: at least 500 running watts and 1,900 starting watts (running plus the 1,400 W start surge, the cautious way to size it). Check both numbers on the spec sheet. A generator rated 2,000 W or more covers it with room to spare.
- Power station: continuous output of at least 500 W and a surge rating that covers about 1,400 W. Pure sine wave output is the safe choice for motors and electronics.
| Power station capacity | Estimated runtime |
|---|---|
| 500 Wh | 2.4 h |
| 1,000 Wh | 4.9 h |
| 2,000 Wh | 9.7 h |
| 3,000 Wh | 14.6 h |
Based on 175 W average draw (running watts × duty cycle) and 85% usable capacity.
- The blower is the part of a gas furnace that needs electricity; without it the furnace will not heat
- Furnace control boards can be sensitive to poor power quality, so an inverter generator or pure sine wave power station is the safer choice
- Most furnaces are hardwired, so they need a transfer switch, interlock or electrician-installed furnace inlet; never backfeed through an outlet
- A 1,000-2,000 Wh power station can run an ECM furnace for several hours; run generators outdoors only, because both the furnace and generator involve combustion and CO risk
Add it to the generator calculator
Questions people ask
What size generator do I need to run a gas furnace?
A 2,000-3,000 W inverter generator usually covers a typical furnace blower and its controls, including the start surge, with some room left for lights or a fridge.
Can a portable power station run my furnace?
Often yes, if it has a pure sine wave inverter and the furnace is connected safely via a transfer switch or furnace inlet. An ECM blower drawing a few hundred watts can run for hours on a 1-2 kWh station.
How much electricity does a furnace fan use per year?
Industry and DOE-cited estimates put a typical furnace fan near 1,000 kWh a year, about 10% of an average home's electricity.
Sources
- Assembly Magazine: Motor manufacturers strive to meet DOE furnace fan standards
- Carrier: Fan Energy Rating (FER) compliant furnaces with ECM blowers
- Eugene Water & Electric Board: Generator sizing considerations
- Massachusetts farm emergency plan, Appendix G: generator information (running/starting watts)
- Virginia Cooperative Extension: Estimating appliance and home electronic energy use (DOE wattage table)