Backup heat when the power's out in January

Most US homes use natural gas, propane, or oil for primary heat. The fuel doesn't need electricity. The blower fan that distributes the heat does. When the grid drops in January, the furnace shuts off within minutes, and the house starts cooling.

A typical 2,000 sq ft house in 20°F outdoor weather drops 10°F per hour without heat once the system stops. By hour 4, indoor temperature is in the 40s. By hour 12, pipes are at risk. By hour 24, the only room above 50°F is the one with a wood stove.

This guide is the backup-heat options that actually work and the one mistake that kills hundreds of people every winter.

The mistake that kills people

Carbon monoxide. Every winter, news reports cover families found dead in their homes after using a generator, charcoal grill, gas grill, propane heater, or kerosene heater indoors during a power outage. CO is colorless, odorless, and accumulates faster than people realize.

Three rules, before any of the options below:

1. Anything that combusts fuel and is not vented through a chimney or sealed exhaust must run outdoors. Generators, charcoal, gas grills, camping stoves. No exceptions, no "I cracked a window."
2. Indoor combustion appliances (wood stove, pellet stove, gas fireplace, vented propane heater) need a working chimney or vent. A blocked chimney puts the same CO into the house as a generator in the kitchen.
3. A battery-powered CO alarm is mandatory before running any combustion backup. Not a hardwired one (no power). A separate battery unit with a fresh battery, on every floor including the basement.

Every option below assumes those three rules are in place.

The backup heat options, ranked by usefulness

Wood stove (the gold standard)

BTU output: 30,000-80,000 BTU/hour, easily heats a 1,500-2,500 sq ft house. Fuel logistics: Cordwood, stored in a shed or stack. 1 cord = 4×4×8 feet = roughly enough for 4-6 weeks of constant winter heating depending on stove and house. Power required: None. Pure radiant + natural convection. CO risk: Low if chimney is in good shape and inspected annually. High if chimney is blocked or the stove is operated incorrectly.

A wood stove with a cord of seasoned hardwood in a shed is the most resilient winter heat backup that exists. It works through any outage, doesn't depend on supply chain, and provides cooking surface as a bonus.

The cost is real: $2,000-4,000 for a quality stove (Jøtul, Lopi, Pacific Energy, Hearthstone), plus $1,500-3,000 for chimney installation if the house doesn't already have one, plus $300-500 per cord of wood.

The constraint: most modern homes don't have a chimney. Adding one is a significant renovation. If your home has an existing brick chimney from a removed wood stove, it's a good candidate; otherwise, the install cost and code requirements push toward other options.

Pellet stove

BTU output: 20,000-50,000 BTU/hour. Fuel logistics: 40-lb bags of compressed wood pellets, stored indoors or in a dry shed. 1 ton of pellets (50 bags) = roughly 6 weeks of constant heat. Power required: Yes. About 100W for the auger and combustion fan. Will not run without electricity unless paired with a small battery backup or generator. CO risk: Same as wood stove; vented through a chimney.

Pellet stoves are cleaner-burning than wood, with thermostat-controlled output. The dependency on power is the catch. A pellet stove paired with a power station that can sustain 100W for 8-12 hours per battery cycle gets you through a typical outage; an extended outage needs a generator paired with the station.

Propane vented wall furnace

BTU output: 10,000-30,000 BTU/hour, sufficient for a single room or small open floor plan. Fuel logistics: External propane tank (100-500 gallon residential). One 100-gallon tank = roughly 2-3 weeks of intermittent use. Power required: Some models are millivolt (no electricity needed); others need a small amount for ignition / blower. Buy the millivolt version explicitly for backup use. CO risk: Low for properly vented units. Sealed-combustion direct-vent models pull combustion air from outside and exhaust outside; safest type.

Vented wall furnaces (Empire, Rinnai, Williams) are the most installable backup option for homes without chimneys. A direct-vent unit goes through an exterior wall, no chimney needed. Cost: $1,500-2,500 installed, plus the propane tank.

Indoor-rated propane catalytic heater (Mr. Heater Buddy class)

BTU output: 4,000-18,000 BTU/hour for the largest "Big Buddy" units. Heats a single room (200-400 sq ft). Fuel logistics: 1-lb propane cylinders or hose to a 20-lb tank. A 20-lb tank lasts roughly 12-18 hours on medium. Power required: None. CO risk: Lower than uncatalyzed propane heaters but not zero. Manufacturer requires a window cracked 1-2 inches. Buddy heaters have an oxygen depletion sensor (ODS) that shuts the unit off if O2 drops below 18%.

Buddy heaters are the most common emergency-only solution because they're cheap ($100-200) and require no installation. The catch is they're rated for indoor use with ventilation, not for sealed indoor use. Bedrooms with the door closed are a no. Open kitchens and living rooms with a cracked window are the rated use case.

Storage: 20-lb propane tanks must be stored outside. Inside the house is a code violation and a real explosion risk in a fire.

Kerosene heater (vented or unvented)

BTU output: 8,000-23,000 BTU/hour. Fuel logistics: Kerosene (K-1 grade), $4-8/gallon, indefinite shelf life if sealed. Power required: None. CO risk: Higher than propane. Unvented kerosene heaters produce more CO than catalytic propane, and the smell is unpleasant. Some states (Massachusetts, others) prohibit unvented kerosene heaters indoors.

Kerosene was the standard backup heat in the 1970s-80s and still works. The downsides (smell, soot, CO) have made it less popular. If you have one already, it's a usable backup; if you're choosing fresh, propane Buddy is the more common pick.

Electric resistance space heater

BTU output: 1,500W = ~5,100 BTU/hour. Heats 150-200 sq ft. Fuel logistics: None (electricity from grid or backup). Power required: Yes. 1,500W continuous. A power station can run one for 1-3 hours per kWh of battery. CO risk: None.

Useful only when you have backup electricity (generator or large power station). A 1,500W heater on a 1,500 Wh battery runs for an hour. Not a multi-day solution, but useful for the "I just need to keep one room above 50°F for the next 4 hours" case.

For sizing the battery against winter heat backup specifically, see the backup power sizing guide and winter solar input math. Solar production drops in the same season heat demand peaks.

What about the fireplace?

A traditional open fireplace produces 5,000-15,000 BTU but pulls 5,000-20,000 BTU of warm room air up the chimney. Net heating effect: usually negative. An open fireplace is not a heat source; it's a romantic atmosphere generator.

A fireplace insert (a sealed wood stove that fits inside the fireplace opening) converts the fireplace into a 30,000-50,000 BTU stove with closed combustion. Cost $2,000-4,000 plus chimney liner. Worth it if you have an existing fireplace; otherwise just install a freestanding stove.

The realistic backup heat plan

For most US households, the practical layered plan looks like:

1. Insulate first. A house that holds heat well needs less backup. Air sealing, attic insulation, and weatherstripping are cheaper per BTU than any backup heat source. Drop your heat loss by 30%, and the backup runs 30% less.
2. One vented appliance for whole-house use. Wood stove if you have a chimney, propane direct-vent wall furnace if you don't, pellet stove if you have power backup. Sized to keep one common space above 60°F.
3. One unvented Buddy-class heater + 20-lb tank for short-duration single-room heat. This is the "we lost power for 6 hours" tool, not the multi-day tool.
4. Battery CO alarms on every floor. Replace the 9V every spring when you change smoke alarm batteries.
5. A "warm room" plan. Pick the room you'll consolidate the household into. Block off other rooms with blankets in doorways. Heating one 200 sq ft room is much cheaper than trying to heat the whole house.

For the "we lost heat in a winter outage" car-stuck-on-the-highway scenario, the answer is different. See the car emergency kit guide.

What to do this weekend

Three things, in order:

1. Test your CO alarms. If any are over 7 years old (sensor lifespan), replace them. Add a battery-powered alarm to any floor that doesn't have one.
2. Identify the warmest room in your house in a no-power scenario. South-facing, fewest exterior walls, smallest. That's the warm-room candidate.
3. If you don't already have a backup heat source, decide which option above fits your house. The most common right answer for a no-chimney suburban house is a propane direct-vent wall furnace + a small Buddy heater. The most common right answer for a house with an existing chimney is a wood or pellet stove.

The cold takes longer to kill you than fire or carbon monoxide, but it kills nonetheless. The plan that keeps a house above freezing for 72 hours is the difference between a hard week and burst pipes.