Mr. Heater Little Buddy review: heat for one small room when a winter outage stops 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 Little Buddy (model MH4B), checked November 1, 2026. Safety guidance comes from the CDC, the Consumer Product Safety Commission (CPSC) and Ready.gov.

When the grid goes down in winter, most central heating stops with it. Even gas furnaces need electricity for the blower and controls. A small propane heater is one of the few ways to put heat into a room with no power at all, and the Little Buddy is the smallest one Mr. Heater lists as indoor-safe.

Small is the point. At 3,800 BTU and 95 square feet, it is built for a tent or an ice-fishing shanty, and in a house that translates to one small room with the door shut. This review covers what those numbers mean, how far a cylinder goes and the ventilation and carbon monoxide rules that come with burning fuel indoors.

Who should buy it

• Households that need to keep a bathroom from freezing or warm a small bedroom for a few hours during an outage.
• Apartment dwellers with limited storage, since it is 5.85 lb and runs on the small green cylinders.
• People who already store 1 lb cylinders for a camp stove and want heat on the same fuel.
• Anyone prepared to run a battery-powered CO alarm in the same room.

Who should skip it

• Anyone heating a living room or a room bigger than about 95 sq ft. The Mr. Heater Portable Buddy covers 225 sq ft and the Big Buddy 450 sq ft.
• Households planning a multi-week outage on propane. Mr. Heater lists no 20 lb tank option for this model, so every 5.6 hours means a new cylinder.
• Residents of Massachusetts and Canada, where Mr. Heater restricts the sale.
• Homes above 7,000 feet, the maximum elevation Mr. Heater lists.

Strengths

• Indoor rating from the maker. Mr. Heater's spec table lists it as indoor-safe, with an oxygen depletion sensor (ODS) and an accidental tip-over shutoff.
• No electricity at all. Push-button Piezo ignition. No batteries, nothing to charge.
• Small footprint. An 8-inch round stand and 5.85 lb weight, easy to move from room to room.
• Predictable fuel use. One setting and a stated 5.6 hours per cylinder make planning simple.
• Common fuel. Standard 1 lb disposable propane cylinders, sold wherever camping gear is sold.

Drawbacks

• One heat level. You cannot turn it down to stretch fuel or up to warm a room faster.
• 1 lb cylinders only. Mr. Heater lists no hose option for a larger tank, so a long outage means a stack of small cylinders.
• Small coverage. 95 sq ft is a bathroom or a small bedroom. Drafty rooms will feel colder.
• It still burns fuel indoors. The ODS is not a carbon monoxide alarm. You need one in the room.
• Restricted sale areas. Not for Massachusetts or Canada, per Mr. Heater.

How it compares

Mr. Heater's four Buddy heaters, all listed by the maker as indoor-safe. Pick by room size and how long each cylinder needs to last. Figures are from Mr. Heater's product pages.

Using it in a long outage

Pick the room and close it off

Choose the smallest room that everyone can use, close the door and hang a blanket over it if it is drafty. Set the heater on a hard, level floor. CPSC advises keeping space heaters at least 3 feet from anything that can burn, which in a bedroom means bedding, curtains and furniture. Do not leave it running in an empty room.

Plan the cylinders

Mr. Heater's figures make the math easy: 3,800 BTU per hour for 5.6 hours is about 21,300 BTU per 1 lb cylinder (our arithmetic). Run it 6 hours a day, morning and evening, and you need about one cylinder a day. Run it 12 hours a day and you need two or more. For a week-long outage that is 7 to 15 cylinders, stored outdoors or in a detached shed.

1. 01Change cylinders outdoors, with the heater off and cool.
2. 02Bring in only the cylinder attached to the heater. Keep spares outside.
3. 03Run it in sessions to take the chill off, then rely on layers and sleeping bags.
4. 04Turn it off before anyone sleeps unless an adult is awake and the CO alarm is running.

When a small heater is not enough

Ready.gov advises going to a community location with power if heat or cold is extreme. If a 95 sq ft room will not stay warm, or someone in the house is elderly, an infant or medically fragile, a warming center is the safer move. Pair any heater with a sealed-battery alarm such as the Kidde COBD10 or First Alert CO710.