Winter Power Outage: Keeping Heat, Water and Phones Going

In a winter outage the problem is not light, it is heat. And most people are surprised to learn that a gas or oil furnace stops too, because its blower, igniter and controls all run on electricity.

The good news: those electrical parts need far less power than heat itself. Keeping a furnace running is realistic on battery backup. Heating a room with electricity is not.

What your heating needs from backup

Heating	Electricity needed	Realistic on batteries?
Gas or oil furnace (forced air)	Blower + controls: ~300–800 W running, surge at start	Yes, with a large station or inverter
Gas or oil boiler (radiators)	Circulator pump + controls: ~60–200 W	Yes, and easier
Pellet stove	~100–200 W running; igniter higher	Yes
Heat pump	2000–5000 W+	Not on portable batteries
Electric space heater	750–1500 W	Minutes, not hours
Electric blanket / heated pad	50–100 W	Yes, for many hours

Blowers vary a lot. Newer furnaces with variable-speed (ECM) blowers draw much less than older ones. The furnace's rating plate lists the blower motor, and a clamp meter reading tells you exactly.

Running a furnace from backup

A furnace does not run continuously. In cold weather it might run 30–60% of the time. A 500 W blower at 50% duty uses about 250 Wh an hour, so a 2000 Wh station keeps it going for roughly six hours, less as it gets colder. Use the inverter size calculator with the gas furnace blower row, and check that surge rating.

Three things to get right:

• Connection. Most furnaces are hard-wired. Having an electrician fit a transfer switch, interlock or approved furnace inlet is the safe way to power one from a generator or power station. Do not improvise by backfeeding a socket.
• Pure sine wave power. Furnace control boards and ECM motors can misbehave on a modified sine wave. Power stations are pure sine; check cheap inverters.
• Grounding. Some furnace ignition controls need a proper ground reference to detect a flame. If a furnace runs from a generator but locks out, that is a known cause for an electrician to look at.

Staying warm without heating the house

When backup cannot cover the furnace, heat people, not rooms:

• Pick one room, ideally small, sunny and away from outside walls. Close its door and cover windows at night.
• Electric blankets and heated pads draw 50–100 W. A 1000 Wh station runs one for 8–15 hours.
• Layers, hats and sleeping bags do more than any small heater.
• Hot water bottles filled before the power goes, or from a gas hob, while it is safe to use.

Carbon monoxide: the winter killer

CO poisoning rises sharply during winter outages. Never heat a home with a gas oven, grill, camp stove, charcoal or a generator. Only use fuel-burning heaters designed and approved for indoor use, follow their ventilation rules, and keep a battery-powered CO alarm near sleeping areas.

Batteries in the cold

• Capacity drops in the cold. Keep power stations and batteries in the heated part of the house.
• Lithium must not be charged below 0 °C (32 °F). Many stations refuse to. Warm it indoors first.
• Lead-acid loses capacity and freezes more easily when discharged. Keep it charged.

Water and pipes

• Drip taps on outside walls and open the cupboards beneath them.
• If the house is getting cold and the outage will be long, shut off the water main and drain the pipes.
• A sump pump may be needed when snow melts. It is a heavy load with a big surge, so include it in your sizing.

Before winter, work through the printable power outage preparation checklist, and for storm outages generally see hurricane and storm season preparation.