Indoor propane heater safety in an outage: the Red Cross advises against it, some makers allow indoor-rated units. Warm up first, then follow the manual.
The honest answer is that the experts split. The American Red Cross advises against it: its winter safety guidance says never use propane-burning devices inside a home. Some manufacturers, including Mr. Heater for its Portable Buddy, allow emergency indoor use of heaters they rate for it, under strict rules. Indoor propane heater safety starts without a flame: layers, blankets, and one warm room. If you still decide on propane, use only an indoor-rated heater with an oxygen depletion sensor (ODS), only where its manual allows, with the ventilation the manual requires and a working carbon monoxide alarm. And the 20 lb tank stays outdoors. The Buddy manual is clear on that.
I'm Mike, a union electrical lineman in New Jersey with 22+ years on the job. I see outages that last long enough for the house to go cold on ordinary work weeks, and I've done mutual aid in multiple states over the years. This page is not a product roundup. It lays out what the Red Cross says, what the manual says, and the order I'd try things in.
The safest heat in an outage is the heat your body already makes. Before any heater:
An electric blanket on a battery is another flame-free option. The planning math is further down.
Two sources people trust say different things, and I'm not going to paper over it.
The Red Cross. Its winter storm tips (American Red Cross of Southern Colorado, January 2026) say: "Never use a generator, grill, camp stove or other gasoline, propane, natural gas or charcoal-burning devices inside a house, garage, basement, crawlspace or any partially enclosed areas." That is general public guidance, and a propane heater is a propane-burning device.
The manufacturer. The Mr. Heater Portable Buddy (MH9BX) owner's manual from Enerco/Mr. Heater labels it a heater "for recreational, commercial and emergency indoor use." It says the heater "may be used for emergency indoor heating when connected to a disposable 1 lb. propane cylinder." The same manual calls it an unvented heater that "uses air (oxygen) from the area in which it is used" and says, in capital letters, "NEVER OPERATE THE HEATER WHILE SLEEPING!"
My take on why the Red Cross says no: too many people skip the safety steps, like the ventilation, the CO alarm, and the tank staying outside. Here is how I treat that split. The blankets-and-one-room plan comes first, because it is what the Red Cross points you to and it costs nothing. If you decide to use an indoor-rated heater anyway, the manual is the minimum, not a suggestion. Follow all of it, not just the convenient parts.
Check your state too. The US Buddy manual says it is "Not for use in a 'dwelling home' in California," and that version is sold for the US except Massachusetts.
A common answer online, sometimes the top-voted one, is to skip the hose and just bring the 20 lb tank inside. The Buddy manual says the opposite:
So indoors, only the 1 lb cylinders the manual allows. The 20 lb tank lives outside. Swapping a 1 lb cylinder means shutting the heater off, letting it cool, and stepping outside. Plan for that.
| Use indoors? | Class | Notes |
|---|---|---|
| Red Cross says no; some makers allow it | Propane units the manufacturer rates for indoor use, with an ODS | Only as the manual allows. Ventilation, clearances, 1 lb cylinders indoors, CO alarm, off while sleeping |
| No | Patio heaters, mushroom heaters, "outdoor only" propane | Stay outside. Full stop. |
| No | Jobsite and construction heaters, open-flame shop heaters | Not living-room gear |
| Electric only if your power plan supports it | Ceramic or oil-filled electric | No combustion CO, but watt-hour and circuit limits are real |
People ask about "Mr. Heater style" units a lot. The honest line: the manufacturer allows emergency indoor use under its rules, and the Red Cross still advises against propane-burning devices indoors. Mis-sizing, blocked ventilation, sealed rooms, and sleeping next to combustion heat are how people get hurt.
For my own house, I lean on electric heat instead of a flame. During outages I've run oil-filled electric heaters off my outdoor generator. I've used a De'Longhi Dragon Digital (TRD40615 series) and an Amazon Basics 7-fin 1,500W, and both do the job well. Last winter we had the coldest stretch in a long time, single digits for over a week. Of course our furnace failed while I was held at work for the blizzard, and the house had no heat while we waited on a part. My wife ran the oil-filled heaters and Dreo electric heaters in each room, and they kept the inside temperature in the low 70s until the part came in. No combustion means no carbon monoxide from the heater itself. Just size the heaters to what your generator or power supply can actually carry.
At our cabin in Pennsylvania, the heat source is a wood-burning stove we replaced a few years ago. The old Ben Franklin stove before it was totally inefficient. In winter the cabin gets cold to the core, sometimes up to 10 degrees colder inside than it is outside. When I get there, the first thing I do is turn on the oil-filled space heaters in the bathroom and the other rooms and get a good hot fire going in the wood stove. It can still take up to half a day to get the place somewhat comfortable, because the whole cabin is cold right down to the studs in the walls. That's the lesson for any cold house: once the structure itself is cold, it takes a lot of heat and a lot of time to bring it back, so it's better to hold heat in than to try to win it back later. The cabin stove is a fixed install. For a camp or backup stove you can move, see the portable wood stove comparison.
An indoor-rated propane heater burns the oxygen in the room and gives off combustion gases and water vapor. The ODS is designed to shut the heater down when oxygen drops too low. That is a safety feature, not permission to run a heater in a sealed room. It also does not measure carbon monoxide. A low-oxygen shutoff is not a CO alarm.
The current Buddy manual (2025 edition) asks for a vent area of at least 9 square inches, about a 3 by 3 inch opening, at the ceiling and at floor level. It also says not to use other fuel-burning appliances inside. "Doesn't cracking a window just let cold air in?" A little. That is the trade, and the opening is small. The manual also notes the heater may shut off above 7,000 feet. Check yours if you live high up.
Planning, not lab claims: treat the manual's limits as the limit. Do not invent ppm numbers or trust anyone who says a short test proves a heater is "fine." Expect some condensation on cold windows. That water vapor is normal for propane heat, and kerosene heaters put out water vapor too. It's another reason not to seal the room.
Not with the Buddy. Its manual says "NEVER OPERATE THE HEATER WHILE SLEEPING!" and not to leave it unattended. The Red Cross gives the same advice for space heaters: turn it off every time you leave the room or go to sleep.
So warm the room in the evening, then turn the heater off at bedtime and let layers and sleeping bags carry you to morning. If anyone wakes with a headache, dizziness, or nausea, get everyone outside and call 911.
Install CO alarms on every level and outside sleeping areas before heater season, plus one in the room where any fuel-burning heater runs. Test them before you light anything.
Check how they are powered. Plug-in alarms fall back to a 9V battery when the power is out, and Kidde's manual for one of its plug-in models calls that battery "short term back-up during a power outage." For a long outage, have at least one alarm that runs on AA batteries or a sealed 10-year battery. The generator carbon monoxide safety page covers this in more detail.
Symptoms that clear when you go outside (headache, dizziness, nausea, a flu-like feeling) are a leave-the-house problem until CO is ruled out. Smoke alarms are separate. You want both.
Leak smell (that rotten-egg odor): shut the valve, get everyone out, no switches or sparks, and call your gas supplier or the fire department from outside.
Most gas furnaces need electricity for the blower and controls, so a dead grid means a dead furnace even with gas in the line. At my house, the furnace and the freezers run off a gas generator we keep outdoors. An EcoFlow DELTA 3 Ultra stays indoors for the essentials: the internet and a few electronics. That is a needs-versus-wants split. A power station keeps essentials running. It does not power a whole home, and I do not ask it to run a space heater all night.
If a generator feeds your furnace or anything else through the house wiring, the main breaker has to be open first. Otherwise the generator's power goes back out through the service drop to the transformer and onto the lines, where it can hurt the lineman working to get you back on. An electrician-installed transfer switch or interlock handles that. Never backfeed through a dryer outlet. Hire an electrician for anything that ties into the panel.
People hope a power station can replace the propane heater. Here is the planning math, not a test result: a space heater on its 1,500-watt setting uses about 1,500 watt-hours every hour. A station with 2,000 watt-hours of capacity would run it a little over an hour before inverter losses, and then nothing else in the house gets power. Electric resistance heat is the fastest way to empty a battery. An electric blanket draws far less than a space heater, so check its label and do the same math.
Run your own numbers in the power station runtime calculator before you count on electric heat overnight. For the generator side, see generator vs power station.
Ice brings down lines and kills the furnace along with the grid. Use this page for the indoor heat decision. Use the ice-storm power, heat, and CO package for the full winter plan.
The Red Cross advises against using propane-burning devices indoors. Some manufacturers allow emergency indoor use of heaters they rate for it, with an ODS, the manual's ventilation, and a CO alarm. Start with layers, blankets, and one warm room. If you use a heater, follow the manual completely.
No. The Buddy manual says never bring a refillable propane cylinder indoors. The 20 lb tank stays outdoors. Indoors, use only the 1 lb cylinders the manual allows.
No. Cracking a window does not change the rating. Outdoor heaters stay outdoors.
Yes. The low-oxygen sensor watches oxygen. A CO alarm watches carbon monoxide. Different jobs.
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