Indoor Heating Safety During a Power Outage

Carbon monoxide cannot be seen or smelled. A person exposed to it may develop headache, dizziness, weakness, nausea, chest pain, or confusion. If a carbon monoxide alarm sounds or anyone has symptoms, move everyone to fresh air, call emergency services, and stay out until responders say it is safe to return.

This page is the stop-condition reference: it identifies equipment that stays outside, unsafe substitutions, warning signs, and reasons to stop or leave. Use Safe Emergency Heating During a Power Outage to compare the available heating paths. Neither page approves a particular appliance or installation; the current manual, local code, and qualified professional responsible for the system take priority.

Stop-condition map

Generator rules that do not change in cold weather

The CDC generator safety guidance says to use generators outside and more than 20 feet from doors, windows, and vents. Point exhaust away from the home.

• Never use a generator in a house, garage, basement, crawl space, shed, or enclosed porch.
• A partially open garage door does not make generator operation safe.
• Do not place a generator beside an open window, dryer vent, fresh-air intake, or neighboring unit.
• Keep the generator dry using a manufacturer-approved open-sided cover. Never wrap or enclose it.
• Shut it down and let it cool before refueling.
• Store fuel in approved containers and in a location allowed by local code.
• Never connect a generator to a household receptacle. That can backfeed utility lines.

Use heavy-duty outdoor cords rated for the equipment and conditions, or have a qualified electrician install an approved transfer method. The Electrical Safety Foundation International portable-generator guidance explains backfeed, cord, and connection hazards.

Smoke and carbon monoxide alarms

Alarms are warning layers, not a substitute for correct equipment placement.

• Follow the alarm manufacturer’s placement and replacement instructions.
• Use battery-powered alarms or alarms with battery backup during outages.
• Test alarms on the schedule in the manual and replace expired units.
• Do not place an alarm where steam, dust, or an appliance manual says it should not go.
• Make sure everyone knows the alarm sound and the outdoor meeting place.

If an alarm sounds, do not silence it and continue heating. Leave first. Call for help from fresh air.

Installed fireplaces and wood stoves

Use an installed fireplace or wood stove only if it has a sound chimney or flue, the required clearances, and current maintenance.

The NFPA heating safety guidance recommends professional annual inspection of heating equipment and chimneys and a three-foot child-free zone around open fires and space heaters.

• Burn only the fuel permitted by the appliance manual.
• Use a sturdy screen where required.
• Keep furniture, curtains, clothing, firewood, and emergency supplies out of the clearance zone.
• Never leave an open fire unattended.
• Place cooled ashes in a covered metal container outdoors, away from the structure.
• Do not install a temporary stove pipe through a window, wall, or roof during an outage.

If the appliance has not been used recently, the chimney may be obstructed or damaged. Choose another safe location rather than treating the outage as a first-use test.

Portable combustion heaters

The phrase “indoor safe” is incomplete. A portable combustion heater may be permitted only in certain rooms, with a certain fuel and cylinder, clearances, ventilation, and constant supervision.

Before use, read the exact manual from the manufacturer. Confirm that the model is allowed in the intended space. Follow all restrictions for sleeping areas, apartments, high altitude, fuel storage, and ventilation.

Do not improvise with:

• a grill, camp stove, or outdoor propane appliance;
• a homemade alcohol burner;
• a candle-and-flowerpot heater;
• a cooking oven used as a room heater;
• a portable wood stove without a code-compliant installed flue;
• any device with a damaged hose, regulator, cord, guard, or safety switch.

Do not assume that opening a window makes a prohibited device safe. Do not sleep while a portable combustion heater runs unless the manufacturer explicitly permits that exact operation.

Electric space heaters

Electric heaters avoid combustion exhaust at the point of use, but their high electrical load can overheat cords, power strips, outlets, and undersized backup systems.

• Put the heater on a stable, level surface.
• Keep the manufacturer’s clearance from bedding, clothing, furniture, and paper.
• Plug directly into an appropriate wall outlet when the manual requires it.
• Do not use an ordinary extension cord or power strip.
• Stop using the heater if the plug, cord, or outlet becomes hot, discolored, loose, or damaged.
• Turn it off before leaving the room or going to sleep unless the manual explicitly permits unattended use.

Do not connect a space heater to a UPS, inverter, power station, or generator merely because the watt number appears to fit. Confirm continuous load, starting behavior, grounding, connection method, and the equipment manuals. A runtime estimate is not electrical approval.

Cooking is not room heating

Never use a gas oven, charcoal grill, gas grill, camp stove, or canned-fuel appliance to heat a room. Cook only with equipment approved for the location and use. Apartment residents should also follow the lease, building rules, fire code, and manufacturer instructions. See the Apartment Emergency Preparedness Guide for a no-cook-first plan.

Decide when to leave

A safe plan includes an exit before conditions become desperate. Leave or seek help when:

• a smoke or carbon monoxide alarm activates;
• a heater cannot be operated exactly as directed;
• anyone has symptoms of carbon monoxide exposure or cold stress;
• the home has fuel, electrical, chimney, or structural damage;
• required medical equipment cannot be powered safely;
• local officials order evacuation or direct residents to a warming center.

Before cold weather, record the heated backup location and the conditions that mean leave in the Outage Readiness Planner.