Mr. Heater Portable Buddy review: one warm room when a winter outage kills the furnace

This is a research-based review, based on manufacturer specs and published data. We do not test products. Specs come from Mr. Heater's product page for the Portable Buddy (model MH9BX), checked November 1, 2026. Safety guidance comes from the CDC, the Consumer Product Safety Commission (CPSC) and Ready.gov.

When a winter storm takes down the grid, most furnaces stop too: even gas furnaces need electricity for the blower and controls. The Portable Buddy is the propane heater people reach for in that situation, because Mr. Heater's spec table lists it as indoor-safe and it runs on the small green cylinders sold everywhere camping gear is sold.

Indoor-rated does not mean risk-free. It still burns fuel indoors, so this review spends as much time on ventilation, carbon monoxide and fuel planning as on the heater itself.

Who should buy it

• Households in cold climates without a wood stove or a generator that can run the furnace, who need to keep one room livable for a few days.
• Apartment dwellers who cannot run a generator outdoors at least 20 feet from the building.
• Anyone who already stores propane for a grill or camp stove and wants a heater on the same fuel.
• People willing to buy and use a battery-powered carbon monoxide alarm in the heated room.

Who should skip it

• Residents of Massachusetts and Canada: Mr. Heater lists both as restricted for this model.
• Homes above 7,000 feet, the maximum elevation Mr. Heater lists.
• Anyone who will not keep a window cracked or will run it unattended while everyone sleeps. Use sleeping bags and a warm room plan instead.
• Households that need to heat a whole house. At 9,000 BTU and 225 sq ft, this is a one-room heater.

Strengths

• Indoor rating from the maker. Mr. Heater's spec table says "Indoor-safe: Yes", with an oxygen depletion sensor (ODS) and an accidental tip-over shutoff.
• No electricity needed. Piezo ignition lights the pilot with a push. Nothing to charge, nothing to plug in.
• Common fuel. It runs on a standard 1 lb propane cylinder, or on a 20 lb tank with a separately sold hose and filter, which is how you make it last through a long outage.
• Two heat settings. 4,000 BTU on low roughly doubles cylinder life compared with 9,000 BTU on high (6 hours versus 3).
• Portable. At 10.6 lb with a fold-down handle, it moves from the living room to a bedroom easily.

Drawbacks

• Short runtime per small cylinder. Three hours on high means four or more 1 lb cylinders a day if you run it continuously. Long outages need the 20 lb tank setup.
• It still makes combustion gases. The ODS shuts the heater off when oxygen drops; it is not a carbon monoxide alarm. You need a separate CO alarm in the room.
• Accessories cost extra. The hose and filter for a 20 lb tank are separate purchases, and Mr. Heater warns that unauthorized accessories void the warranty.
• Restricted sale areas and elevation limit. Not for Massachusetts, Canada or above 7,000 feet, per the maker.
• Small coverage. 225 sq ft is one room with the door closed. Rooms with high ceilings or drafty windows will feel colder.

How it compares

Mr. Heater makes the three closest alternatives, all listed as indoor-safe by the maker. Pick by room size and how long each cylinder needs to last.

Using it in a long outage

Set up a warm room before you light it

Pick one room, ideally an interior room with few windows, and close its door. Hang a blanket over the doorway if needed. Put the heater on a hard, level floor, away from bedding, curtains and anything that can burn. Mr. Heater's coverage figure of 225 sq ft assumes an enclosed space, so a closed room is the point.

Plan the fuel

Use Mr. Heater's burn rates to size your propane. On low, the heater uses 0.044 gallons an hour; on high, 0.099. A 20 lb tank holds 20 lb of propane, and at roughly 4.2 lb per gallon that is about 4.7 gallons (our arithmetic, not a Mr. Heater figure). Running on low for 12 hours a day, that is roughly 9 days per 20 lb tank; on high, about 4. With only 1 lb cylinders, 12 hours a day on low takes two cylinders a day, and on high four.

1. 01Store full cylinders outdoors or in a detached shed, never in the living space.
2. 02Change cylinders outdoors with the heater off and cool.
3. 03Run on low whenever the room holds temperature; switch to high only to warm it up.
4. 04Turn the heater off before sleeping unless an adult is awake and the CO alarm is running.
5. 05Layer clothing and sleeping bags so the heater is a supplement, not the only plan.

Know the limits

Ready.gov advises going to a community location with power if heat or cold is extreme. If the room will not stay above about 50°F, or anyone in the house is elderly, an infant or has a medical condition, a warming center may be safer than a propane heater. Check with local officials about heating locations.

Pair this heater with a sealed-battery CO alarm such as the First Alert CO710, and keep a fire extinguisher within reach of the warm room.