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Propane and kerosene heaters burn fuel and produce carbon monoxide, so proper ventilation is essential any time you run one in a garage or other enclosed space. Always follow the manufacturer’s instructions, install a working carbon monoxide detector near the space, and check your local fire and building code before operating a fuel-burning heater indoors.
For most uninsulated garages, a portable propane heater like the Mr. Heater Big Buddy delivers the best mix of low upfront cost and low cost-per-hour of heat, provided the space is properly ventilated. A hardwired electric garage heater is the better call if you already have a 240-volt circuit and want thermostat-controlled, hands-off warmth with no combustion byproducts, while a high-output kerosene forced-air heater makes the most sense for a large, drafty detached garage or barn that needs to go from freezing to workable fast. There is no single best garage heater — the right pick depends on your space’s size, your electrical setup, and how often you’ll actually run it.
At a Glance: Our Picks
- Best Overall — Dyna-Glo Delux KFA80DGD (kerosene): 80,000 BTU/hr and coverage up to 1,900 sq ft make this the heater that can actually warm a large, uninsulated detached garage.
- Best Budget — Mr. Heater Big Buddy MH18B (propane): $121.80, no installation, and a built-in low-oxygen shutoff sensor for a smaller garage you heat occasionally.
- Best Upgrade — Dr. Infrared DR-910F (electric, 240V): Thermostat-controlled, zero combustion byproducts, and the right pick if you already have the electrical service for a permanent workshop heater.
Propane vs. Electric vs. Kerosene: Quick Comparison
| Heater | Price | BTU Output | Coverage Area | Fuel Cost Profile | Safety Features |
|---|---|---|---|---|---|
| Mr. Heater Big Buddy MH18B (propane) | $121.80 | 4,000–18,000 BTU/hr | Up to 450 sq ft | ~$0.53/hr at max output (propane, $2.67/gal) | Low-oxygen shutoff sensor, tip-over safety switch, thermal shutdown |
| Dr. Infrared DR-910F (electric) | $599.99 | 30,000 BTU/hr (10,000W, 240V) | Up to 700 sq ft | ~$1.84/hr at max output (electricity, $0.1844/kWh) | UL & cUL listed, thermally protected enclosed motor, remote thermostat |
| Dyna-Glo Delux KFA80DGD (kerosene) | $229.99 | 80,000 BTU/hr | Up to 1,900 sq ft | ~$3.20/hr at max output (kerosene, ~$5.40/gal) | Flame-out sensor, overheat auto shut-off valve, CSA certified |
How to Choose a Garage Heater for an Uninsulated Space
An uninsulated garage or workshop behaves nothing like a bedroom or a den, which is why the specs that matter for a small indoor space heater don’t translate directly here. Heat leaks out through an uninsulated garage door, gaps around windows, and often a shared wall with the outdoors on two or three sides, so the coverage-area number on the box assumes far more heat loss than a sealed, insulated room would have. Before comparing BTU output, walk your space and note three things: square footage, how tight the garage door seals, and whether you have (or can add) a 240-volt outlet.
Fuel-burning heaters (propane and kerosene) generally deliver more heat per dollar of upfront cost and are easier to move between a garage and a job site, but they need real airflow and a carbon monoxide detector nearby. Electric heaters cost more to buy and to run, but they don’t produce combustion byproducts, don’t need refueling, and can be left running unattended with a thermostat doing the work. If your garage is attached to your house and shares a wall or ductwork with living space, that alone is a strong argument for electric — not because propane or kerosene are unsafe when used correctly, but because the ventilation requirements are harder to guarantee in an attached structure.
If your garage doubles as a spot to run a backup generator during outages, it’s worth reading our comparison of portable generators — the same ventilation logic that applies to fuel-burning heaters applies there too.
Mr. Heater Big Buddy MH18B: Best Budget Pick for a Smaller Garage
The Big Buddy MH18B is a portable radiant propane heater with three settings spanning 4,000 to 18,000 BTU per hour, priced at $121.80. It’s rated for roughly 450 sq ft of coverage and runs on two 1-lb propane cylinders that thread directly into the unit, or on a 20-lb tank with a separate hose and filter accessory. It ships with a built-in low-oxygen shutoff sensor that cuts the heater off if oxygen levels drop too low, plus a tip-over safety switch and a thermal shutdown system.
- Pros: Lowest upfront price of the three; indoor-rated with a low-oxygen shutoff sensor and tip-over switch; no installation required; cheapest fuel cost per hour of heat of the three, per the cost table below.
- Cons: 450 sq ft rated coverage is undersized for a large detached garage or a two-car workshop; 1-lb cylinders run out quickly on the high setting unless you add a hose adapter for a 20-lb tank; radiant heat warms what’s in front of it rather than the whole room evenly.
Standout call: For a one-car garage or a workbench corner you’re heating for an hour or two at a time, this is the heater to buy, full stop. Named dealbreaker: if your garage runs larger than roughly 450 sq ft or has limited airflow, the Big Buddy’s coverage and ventilation needs make it the wrong tool for the job — step up to the kerosene heater instead.
Dr. Infrared DR-910F: Best Upgrade for a Full-Time Workshop
The DR-910F is a hardwired 240-volt electric heater rated at 10,000 watts, with a manufacturer-listed output of 30,000 BTU per hour and coverage up to 700 sq ft. It lists for $599.99, mounts to a wall or ceiling bracket, and includes a remote-controlled thermostat with a 50–85°F range so it can hold a set temperature on its own. It’s UL and cUL listed, and the manual calls for 6 AWG copper wiring on the circuit.
Because it’s resistive electric heat, there’s no flame, no fuel to store, and no carbon monoxide to worry about — which matters if your garage shares a wall or ductwork with the house. The tradeoff is cost: it’s the most expensive heater here to buy, and the $599.99 sticker doesn’t include the electrician’s bill if you don’t already have a spare 240-volt circuit near the garage.
- Pros: No combustion, no fuel to buy or store, and no carbon monoxide risk; thermostat holds a set temperature automatically; largest rated coverage area of the three at 700 sq ft; UL and cUL listed.
- Cons: Highest upfront cost, before any electrical work; permanently wall- or ceiling-mounted, not something you move between the garage and a job site; most expensive to run per hour of heat delivered, per the cost table below.
Standout call: This is the heater for someone who treats their garage as a daily workshop and wants to set a temperature and forget it, not for occasional weekend warm-ups. Named dealbreaker: if you don’t already have a 240-volt circuit in the garage, budget for an electrician on top of the sticker price, or this pick stops being an “upgrade” and turns into a bigger electrical project than the heater itself.
Dyna-Glo Delux KFA80DGD: Best Overall for Large, Uninsulated Spaces
The KFA80DGD is a portable forced-air kerosene heater rated at 80,000 BTU per hour with coverage up to 1,900 sq ft, priced at $229.99. It holds 5 gallons of fuel with roughly 9 hours of runtime on a full tank, and it’s built to run on 1K kerosene as well as #1/#2 diesel, fuel oil, Jet-A, or JP-8, which is useful if kerosene isn’t easy to find locally. Safety features include an integrated flame-out sensor, an overheat auto shut-off valve, and CSA certification, plus a built-in thermostat and fuel gauge.
- Pros: Highest raw BTU output of the three by a wide margin; largest rated coverage area at up to 1,900 sq ft, built for big, drafty spaces; flame-out sensor and overheat shutoff are standard; runs on several fuel types.
- Cons: Strong fuel odor and combustion byproducts make it a poor fit for a garage attached to living space; loud forced-air fan, not a background heater; requires hand-refueling from a stored fuel container rather than a piped supply; highest per-hour running cost of the three fuels, per the cost table below, despite the biggest BTU number.
Standout call: For a large, detached, uninsulated garage or barn that needs to go from cold to workable fast, this is the most decisive pick on this list — nothing else here puts out this much heat. Named dealbreaker: don’t run this in a garage attached to your house or sharing air with living space; the odor and ventilation demands are real, and we’re naming that plainly rather than splitting the difference between products.
Garages also tend to run damp as well as cold, especially once a fuel-burning heater is adding moisture from combustion. If that’s a recurring issue in your space, a standalone dehumidifier is worth budgeting for alongside whichever heater you pick.
Original Data: What Each Heater Actually Costs to Run
BTU ratings tell you how much heat a unit can put out, not what that heat costs. We built the table below by taking each heater’s manufacturer-rated maximum output and running it through named, current fuel prices and standard energy-content figures for each fuel — the same kind of math a utility or fuel supplier would use to estimate your bill, just applied heater by heater instead of home by home.
Fuel Prices and Energy Content Used
| Fuel | Price Used | Source | Energy Content |
|---|---|---|---|
| Propane | $2.67/gal | EIA residential propane price survey, week ending March 30, 2026 (EIA pauses weekly publication April–September) | 91,420 BTU/gal (U.S. DOE Alternative Fuels Data Center, higher heating value) |
| Electricity | $0.1844/kWh (18.44¢) | EIA Electric Power Monthly, U.S. average residential price, May 2026 | Billed and consumed directly by the watt; no conversion needed |
| Kerosene | ~$5.40/gal | Average of current K-1 kerosene retail supplier pricing, $5.20–$5.69/gal, Northeast markets (gethomeheat.com, accessed August 2026) — regional proxy, since national kerosene retail data is published far less consistently than propane or electricity | 135,000 BTU/gal (EIA thermal conversion factor: 5.670 million BTU per 42-gallon barrel) |
Cost per Hour at Maximum Output
| Heater | Fuel Burned per Hour at Max Output | Cost per Hour at Max Output | Cost per 10,000 BTU Delivered | Cost for an 8-Hour Overnight Run |
|---|---|---|---|---|
| Mr. Heater Big Buddy MH18B (18,000 BTU/hr, propane) | ~0.20 gal propane | $0.53 | $0.29 | $4.24 |
| Dr. Infrared DR-910F (10,000W, electric) | 10 kWh | $1.84 | $0.61 | $14.75 |
| Dyna-Glo Delux KFA80DGD (80,000 BTU/hr, kerosene) | ~0.59 gal kerosene | $3.20 | $0.40 | $25.61 (≈ one full 5-gal tank) |
Two things stand out. First, propane is the cheapest fuel per unit of heat delivered in this comparison, even though the Big Buddy has the smallest BTU rating of the three — a smaller flame burning a cheaper fuel can still win on cost per 10,000 BTU. Second, the kerosene heater’s 5-gallon tank and roughly 9-hour runtime line up almost exactly with an 8-hour overnight burn at full output, which is a useful gut check if you’re planning to run one through a cold night in the shop. These figures assume continuous operation at each heater’s maximum rated output; a thermostat-controlled unit like the DR-910F, or a Big Buddy run on its low or medium setting, will typically cost less per hour in real use than the maximum-output numbers above.
How We Compared
We did not physically test these three heaters side by side. This comparison is built from manufacturer-published specifications, current retail listings, and named fuel-price data from the sources cited above, cross-checked across multiple retailer and manufacturer pages for each model. Our full process for sourcing specs, pricing, and safety information is explained on our editorial standards page.
Prices are approximate, current as of publication, and change frequently — confirm the latest price with the retailer before buying.
Frequently Asked Questions
Is it safe to run a propane or kerosene heater in a closed garage?
Fuel-burning heaters need fresh-air ventilation to run safely, so “closed” is the problem, not the fuel type itself. Crack a window or the garage door, follow the clearance and ventilation instructions in the manufacturer’s manual, and install a carbon monoxide detector in the space any time a propane or kerosene heater is running.
What size garage heater do I need for an uninsulated space?
Match the heater’s rated coverage area to your garage’s square footage, then round up rather than down, since uninsulated walls and a standard garage door lose heat much faster than an insulated room of the same size. In this comparison, that’s roughly 450 sq ft for the Big Buddy MH18B, 700 sq ft for the DR-910F, and up to 1,900 sq ft for the KFA80DGD, per each manufacturer’s rating.
Do I need a 240-volt circuit for an electric garage heater like the DR-910F?
Yes. The Dr. Infrared DR-910F is a hardwired 240-volt unit rated at 10,000 watts, and its manual specifies 6 AWG copper wiring for the circuit. If your garage only has standard 120-volt outlets, factor in the cost of adding a 240-volt circuit before comparing its price to a portable propane or kerosene heater.
Can a kerosene heater run all night in a garage?
Only if you follow the manufacturer’s instructions on ventilation, clearance, and unattended operation, and have working carbon monoxide detection in place — check the specific model’s manual before leaving any fuel-burning heater running unattended or overnight. The Dyna-Glo Delux KFA80DGD’s 5-gallon tank holds roughly 9 hours of fuel at full output, which is close to a typical overnight run.
Which fuel is cheapest to run a garage heater on?
Based on our cost-per-10,000-BTU calculation using current propane, electricity, and kerosene prices, propane came out cheapest per unit of heat delivered, kerosene was in the middle, and electricity was the most expensive per BTU in this comparison — though electricity has no fuel to buy or store and produces no combustion byproducts, which has its own value.
Do I still need a carbon monoxide detector if my heater has a low-oxygen shutoff sensor?
Yes. A low-oxygen shutoff sensor, like the one built into the Mr. Heater Big Buddy, is a safety feature on the appliance, not a substitute for a separate carbon monoxide detector in the space. Follow the manufacturer’s instructions and your local code for both.
Also worth a look if fuel-cost math like this is useful to you: our wood vs. propane vs. smokeless fire pit comparison runs a similar cost breakdown for outdoor propane use, and you can browse every comparison in this space in our Heating & Cooling category.
Published August 3, 2026. Updated August 3, 2026.
