Indoor-safe propane heaters

What "indoor-safe" means

Portable heaters sold as indoor-safe in the United States have two safety devices:

• An oxygen depletion sensor (ODS) that shuts the heater off if oxygen in the room falls too low.
• A tip-over switch that shuts it off if it is knocked over.

What the label does not mean: that it cannot make carbon monoxide, that it needs no ventilation, or that it can run all night while you sleep. The oxygen sensor is not a carbon monoxide detector.

Canada and other places with different rules

Certification is country by country. The same heater sold as indoor-safe in most of the United States is not approved for indoor use in Canada or Massachusetts, where a separate version labelled for outdoor use is sold. Other places have their own restrictions. Many rental leases, condo rules and insurance policies ban fuel-burning portable heaters and indoor propane outright. Check the certification mark and wording on the unit you are buying, and check your own building's rules.

The rules that come with one

1. Follow the manual's ventilation instructions exactly. They specify an opening to outside air sized to the heater.
2. Have a working battery CO alarm in the same room, and a second near where people sleep. See battery CO alarms on Amazon.
3. Never run it while anyone is asleep, and never leave it unattended. Warm the room, turn it off, then go to bed in a good sleeping bag.
4. Keep it clear of bedding, curtains, furniture and anything that burns, by the distances in the manual. Set it on a hard, level surface.
5. Keep children and pets away from it.
6. Use only the small 1 lb cylinders indoors, unless the maker's hose and filter kit and your local rules allow otherwise. Large barbecue tanks stay outside. Change cylinders outdoors.
7. If the alarm sounds or anyone feels a headache, dizziness or nausea, turn it off, get everyone outside and call 911.

These heaters also work poorly at high altitude, and the oxygen sensor may shut them off there.

How much heat, how much fuel

A heater on a low setting of about 4,000 BTU warms a small closed room. It burns through a 1 lb cylinder in roughly five to six hours on low and about half that on high. For a two-week outage that is a lot of cylinders, which is why this is a way to take the edge off one room for a few hours a day, not a replacement for the furnace.

Burning propane also releases water vapour. Expect condensation on cold windows.

Picks

These are the models most often used for this job in the United States. Each has an oxygen depletion sensor and a tip-over switch. The maker states that indoor use is not approved in Canada or Massachusetts, where a separate outdoor-only version is sold.

Safer ways to get the same result

• Insulate the people. A sleeping bag rated to −20 °C or lower works all night with no fuel and no risk. See cold-weather sleeping bags on Amazon.
• Shrink the room and seal it, as in heat without power.
• A professionally installed wood stove, if you own the home, is the dependable long-term answer.
• Leave early for somewhere with heat. See −30 with no heat.