Indoor Heating Safety During a Power Outage
Safety rules for generators, installed wood stoves, portable heaters, smoke alarms, carbon monoxide alarms, and the decision to leave a cold home.
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
| Equipment or condition | Gate before use | Stop, leave, or get help when |
|---|---|---|
| Generator | A compliant outdoor location, approved connection, correct load, and current manual | Exhaust can reach an opening, the unit must be enclosed, a connection is improvised, or an alarm activates |
| Installed fireplace or stove | Current inspection, sound chimney or flue, required clearance, and permitted fuel | Smoke enters the room, the flue may be obstructed, the system is damaged, or supervision cannot continue |
| Portable combustion heater | The exact model is permitted in that room with the required fuel, clearance, ventilation, and supervision | A hose or guard is damaged, an alarm or symptom appears, or any manual condition cannot be maintained |
| Electric space heater | Stable placement, required wall outlet, clearance, and an electrical source approved for the load | A plug, cord, or outlet becomes hot, loose, discolored, or damaged, or the backup source cannot support it |
| The home | Working alarms, an available heated destination, and care needs that remain supported | Temperature or medical needs become unmanageable, equipment cannot be used as directed, or officials order evacuation |
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. Turn portable heaters off before sleeping. Follow the exact manual for all additional restrictions.
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 at least three feet from bedding, clothing, furniture, paper, and other combustible material, or farther when the exact manual requires more clearance.
- Plug the portable electric heater directly into an appropriate wall outlet.
- Never use an 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 it unattended and before going to sleep.
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, make a paper card with a heated destination and alternate, transportation for each person, the conditions that mean leave or call for help, and any care or device-provider instructions needed if support fails. Confirm that the destination can meet the household’s access and care needs.
Use the Outage Readiness Planner for fixed outage choices and suggested actions. Keep the card separately: the planner does not store destinations, transport contacts, care instructions, or leave triggers.
Before using stored heated bedding, the electric-blanket pre-use gate checks the matching controller, manual, recall details and visible condition. Some exact manuals prohibit generator or inverter use.
