Space Heaters and Propane Heaters: Safe Use in a Winter Storm

An electric space heater can be used safely in a storm if it carries a testing-lab mark, has tip-over and overheat shut-off, plugs straight into a wall outlet and sits 3 feet from anything that can burn, per NFPA and CPSC. It needs power, though. Indoor-rated propane heaters are allowed only as their manuals and local rules permit.

What safety features should an electric space heater have?

NFPA’s electric space heater checklist is the clearest buying guide from an official source. Each feature below comes from the named source.

The testing-lab mark is where “UL listed” and “ETL listed” come in. OSHA keeps the list of Nationally Recognized Testing Laboratories, and it includes UL LLC, Intertek Testing Services (the ETL mark) and CSA Group. Any of those marks shows the heater was tested by a recognized lab.

NFPA’s tip sheet also notes that two in five deaths in space heater fires involve portable electric space heaters. USFA reports that for 2017 to 2019, portable heaters caused only 3% of home heating fires but 41% of fatal heating fires.

How do you use a space heater safely?

These rules come from CPSC, with additions from NFPA and USFA where noted.

Give it room. CPSC says to keep beds, sofas, curtains, papers and clothes at least 3 feet from the front, sides and rear of the heater. NFPA’s tip sheet says 3 feet from anything that can burn, including people, and recommends a 3-foot kid-free zone.

Plug it into the wall. CPSC says the plug must fit tightly in the wall outlet, and to never power the heater with an extension cord or power strip. USFA adds: do not plug anything else into the same circuit, because that can cause overheating.

Watch the cord. CPSC says never to run the cord under rugs or carpeting. During use, check whether the plug, cord, outlet or faceplate is hot. If the plug or outlet is hot, stop using the heater and have an electrician check it; if the cord is hot, have the heater repaired.

Keep it stable and dry. Place it on a stable, level surface where it will not be knocked over. CPSC says to keep electric heaters away from water and never touch one if you are wet.

Turn it off. CPSC says never to leave a heater running unattended or while you sleep. NFPA and USFA say to turn it off when you leave the room or go to bed. NFPA’s electric heater sheet says to unplug it too.

Can you run a space heater during a power outage?

Only with a power source that can carry it. An electric heater does nothing when the grid is down, and it is one of the hungrier appliances in a home. Champion’s generator wattage chart lists a space heater at 750 to 1,500 running watts.

That leaves three routes, each with limits:

1. A generator through a transfer switch. The American Red Cross says to have an electrician install a power transfer switch to connect a generator to house wiring. The heater then plugs into a wall outlet as usual, which keeps it within the CPSC rule. The generator itself still runs outdoors, at least 20 feet from the house, as CPSC directs.
2. A generator with cords. CPSC’s generator guidance connects appliances through heavy-duty outdoor extension cords. Its heater guidance says never to power a heater with an extension cord. Those two rules clash, so follow your heater’s manual on cords and do not improvise.
3. A battery power station. A power station has its own outlets, so the heater plugs straight in. At 750 to 1,500 W, a heater is a heavy load for any battery. Our sister site Solar Home explains what size solar generator you need for loads like this.

Never plug a generator into a wall outlet to feed the house. CPSC calls that backfeeding and warns it can electrocute utility workers and neighbors. Our guide to portable generators for winter outages covers sizing and safe connections.

If you have no safe way to power a heater, warm clothing is the fallback. Ready.gov advises layers, and our guide to heated jackets, vests and gloves covers battery-heated clothing.

Can you use a propane heater indoors?

Only a heater that is designed, certified and labeled for indoor use, used exactly as its manual says. Everything else, including patio heaters, grills and camp stoves, stays outside. NFPA says gas and charcoal grills produce CO and belong outside only. Ready.gov says never to heat your home with a gas stovetop or oven.

What CPSC says about indoor-rated propane heaters

CPSC says unvented gas space heaters need oxygen depletion sensors (ODS) to help prevent CO from inefficient combustion. In a 2002 alert, CPSC said an ODS closes the gas valve and shuts off the heater if oxygen drops below 18 percent.

CPSC said ODS heaters are designed for indoor use, identified by labels such as “Designed for Indoor Use,” “Low Oxygen Automatic Shut-Off System,” “Oxygen Depletion Sensor” or “CSA 4.98.” It stressed that users must follow the maker’s ventilation instructions, and it still recommends shutting heaters off before going to sleep.

CPSC also says to follow the manufacturer’s instructions for combustion air, and warns that an oversized heater could use up the available oxygen and produce excess CO.

What one maker’s manual requires

The Mr. Heater Portable Buddy (model MH9BX) manual shows how specific these rules get. It describes the heater as an unvented, gas-fired portable heater for recreational and emergency indoor use, and says:

• It may be used for emergency indoor heating when connected to a disposable 1 lb propane cylinder.
• It needs a minimum vent area of 9 square inches at the ceiling and at floor level while running. Do not use it in unventilated areas.
• Clearances to combustibles are 30 inches above, 24 inches in front and 6 inches at the sides.
• Never operate it while sleeping, and never leave it unattended.
• In a bathroom, use the low setting only.
• Do not use other fuel-burning appliances inside at the same time.

Other models set other limits, so read the manual for the heater you actually own.

State and local rules vary

Rules on unvented heaters are not the same everywhere. The Buddy manual itself says the heater is for U.S. sale except Massachusetts. Check your state and local fire code, or ask your local fire department, before you buy or use any unvented fuel-burning heater. Kerosene heaters are not covered on this page.

Our carbon monoxide safety guide lists CO symptoms and where CPSC and NFPA say to put alarms.

More storm steps, from blocked vents to backup power, are in our winter storm preparedness guide.