Backup NorthWill it run my furnace, fridge or sump pump?
Short answer: fridges, CPAPs and internet, yes, easily. Furnace blowers and sump pumps, usually, with the right setup. Well pumps and electric heat are hard.
| Item | Typical running watts | Start-up surge | Energy per day | Plug in? |
|---|---|---|---|---|
| Modern fridge | 100 to 200 W while running | Up to about 1,000 W briefly | About 1 to 2 kWh | Yes |
| Chest freezer | 60 to 150 W while running | Up to about 800 W | About 0.5 to 1.2 kWh | Yes |
| Gas furnace blower | 300 to 800 W | Moderate | Several kWh on a cold day | Usually hardwired |
| Sump pump (1/3 hp) | About 800 W | 1,300 to 2,000 W | Depends on how often it runs | Often plugs in |
| CPAP | 30 to 60 W (more with heated humidifier) | None | About 0.3 to 0.8 kWh a night | Yes |
| Internet modem + router | 10 to 25 W | None | About 0.3 to 0.6 kWh | Yes |
| Well pump (1/2 to 1 hp) | 1,000 to 2,000 W | Up to about 3× running | Depends on water use | Usually 240 V hardwired |
| Electric baseboard heater | 1,000 to 2,000 W each | None | Very high | Hardwired |
General estimates from common appliance ratings. Your appliance's nameplate or a plug-in watt meter gives the real figure.
Furnaces
A gas or propane furnace still needs electricity for its blower, igniter and controls. Most are hardwired, so the safe way to run one from backup power is a furnace inlet or transfer switch installed by a licensed electrician. Modern furnaces with electronic controls are sensitive to power quality, so use a "pure sine wave" source. All current power stations from major brands are. Some furnaces also need a proper ground and correct polarity to ignite, so ask the electrician to check that.
Sump pumps
The pump only runs when water rises, so total energy is often modest, but the start-up surge is high. Check that the station's surge rating covers it with room to spare. In a spring thaw or heavy rain, a pump can cycle every few minutes, so plan for more capacity, or a battery-backed secondary pump.
Well pumps
Many rural wells use a 240-volt pump with a large start-up surge. Only some larger stations, or two linked units, offer 240 V. A generator or a whole-home battery is often the more practical choice. Fill bathtubs and jugs before a forecast storm.
Electric heat
Baseboards and electric furnaces draw far more than any portable battery can sustain. For heat in an outage, rely on a gas furnace with backup power, a wood stove, or a heater rated for indoor use. Never use a camp heater or barbecue indoors.