Which Garage Heater Is Best: Electric, Gas or Propane?
The best garage heater depends on how often you use the space and what fuel you already have. On fuel cost alone, natural gas is the cheapest heat this winter, propane comes next, and electric resistance heat costs the most per unit of heat. Whatever the fuel, the U.S. Consumer Product Safety Commission has warned that unvented fuel-burning heaters pose the greatest threat of carbon monoxide poisoning, so a vented, permanently installed unit is the safer choice for a garage you heat often.
The fuel math is easy to run with current federal numbers. Using the U.S. Energy Information Administration's heat content factors, its October 5, 2026 Pennsylvania residential propane price of $3.150 a gallon, and its Winter Fuels Outlook forecasts for the Northeast of 26.19 cents per kilowatt-hour and $16.12 per thousand cubic feet of natural gas, one million Btu of fuel energy costs about $76.76 as electricity, $34.44 as propane and $15.56 as natural gas, before any appliance losses. Somerset County garages also stay cold longer than Pittsburgh's: NOAA's 1991 to 2020 normals show 42.9 days a year at Meyersdale and 55.1 at Hidden Valley when the high never gets above 32°F, compared with 31.7 at Pittsburgh International Airport.
What Is a Garage Unit Heater?
A garage unit heater is a permanently installed heater, hung from the ceiling or mounted high on a wall, with a fan that blows heated air across the space. It runs on a thermostat like a furnace. A portable heater, by contrast, is one you plug in or set on the floor and move around.
Unit heaters come in electric, natural gas, propane and hot water versions. Van Bremen's installs garage heaters in "various types such as electric, gas, or propane," and its heating page says the team will assess the garage layout, recommend the most suitable heater, and handle installation, ventilation and code compliance.
How Do Electric, Gas and Propane Garage Heaters Compare?
Here is how the three fuels stack up using the EIA figures above:
Fuel | Price used | Cost per million Btu of fuel |
Electricity | 26.19 cents per kWh (Northeast winter forecast) | $76.76 |
Propane | $3.150 per gallon (Pennsylvania, Oct. 5, 2026) | $34.44 |
Natural gas | $16.12 per thousand cubic feet (Northeast winter forecast) | $15.56 |
The EIA's propane price excludes taxes, and fuel-burning heaters lose some heat out the vent, so the gap between electric and fuel narrows in practice. Even so, propane stays cheaper than electric resistance unless a heater turns less than about 45% of its fuel into heat. Electric resistance turns each kilowatt-hour into 3,412 Btu, the EIA conversion, and no more.
That does not rule electric out. Electric heaters need no gas line, vent or tank, so they suit a small garage or a space you heat a few hours at a time. Gas and propane make more sense when the garage is a workshop you use most winter days. If your home has no natural gas service, propane is the fuel-burning option, and the guide to heating system options that save energy and money covers efficient choices for heating the house itself.
What Is the Difference Between Vented and Unvented Garage Heaters?
Every fuel-burning heater makes combustion gases, including carbon monoxide. The question is where those gases go.
Unvented heaters release combustion gases into the space. CPSC has warned that unvented heaters burning natural gas, liquefied petroleum and other fuels pose the greatest threat of carbon monoxide poisoning because they need a constant supply of fresh air to operate safely.
Power-vented heaters use a fan to push exhaust out through a vent pipe. Modine sells its Hot Dawg power-vented models from 30,000 to 125,000 Btu per hour for residential and commercial use.
Separated combustion heaters go a step further. Modine says its Hot Dawg HDS pulls in 100% outside air for combustion and lists residential garages, workshops and auto repair bays among its uses. It comes in six sizes from 30,000 to 125,000 Btu per hour and runs on natural gas or propane.
Separated combustion keeps the burner from drawing its air from the garage itself. The carbon monoxide and furnace safety guide covers alarms and other steps that apply to any fuel-burning appliance.
What Code Rules Apply to a Gas Garage Heater?
The International Residential Code, in section M1307.3, requires appliances with an ignition source to be elevated so the ignition source sits at least 18 inches above the garage floor. The exception is an appliance listed as flammable vapor ignition-resistant. A companion section, M1307.3.1, says an appliance must not be installed where a vehicle could damage it unless it is protected by an approved barrier.
The exception's name points to the reason: the rule keeps pilots and burners away from flammable vapors, such as gasoline fumes, near the floor.
Pennsylvania's Uniform Construction Code moved to the 2021 International Codes on January 1, 2026, and the local code official has the final say on any installation. A unit heater hung near the ceiling keeps its burner well above the 18-inch line and out of the vehicle's path.
Can a Boiler Heat a Garage?
Yes, if your home has a hot water boiler. A hydronic unit heater uses hot water from the boiler instead of its own burner. Modine's Hot Dawg H2O, for example, is a ceiling-mounted hydronic heater for residential garages, workshops and basements. It runs on 115 volts, handles water up to 200°F, and moves air at three blower speeds from 280 to 710 cubic feet per minute.
With no burner in the garage, a hydronic heater adds no combustion gases or ignition source there. The boiler needs enough capacity for the extra load, which a technician checks before adding a zone.
A ductless mini split is another way to heat a garage, and it can cool the space in summer. The guide to using ductless mini splits to supplement an existing system explains how they work alongside a central system.
What Safety Steps Matter for Portable Garage Heaters?
If you use a portable heater while you decide on a permanent one, CPSC's December 2025 winter safety guidance applies:
Keep portable heaters at least 3 feet from anything that can burn.
Plug electric heaters directly into a wall outlet, never a power strip.
Never run a portable generator in a garage, even with the door open.
Install carbon monoxide alarms on each level of the home and outside sleeping areas, and test them monthly.
An insulated garage holds heat better, whatever heater you choose. The guide to improving your home's insulation covers the basics.
FAQ
What is the cheapest way to heat a garage?
On fuel cost per million Btu, natural gas is cheapest, using EIA's current prices and forecasts. Electric heat costs the most per Btu, but it needs no gas line, vent or fuel tank.
Is it safe to use a propane heater in a closed garage?
An unvented propane heater releases combustion gases into the space, and CPSC warns unvented fuel heaters carry the greatest carbon monoxide risk. A vented or separated combustion unit sends exhaust outside.
How high does a gas garage heater need to be?
The International Residential Code requires the ignition source to sit at least 18 inches above the garage floor unless the appliance is listed as flammable vapor ignition resistant.
Does a hydronic garage heater need a boiler?
Yes. Modine describes its Hot Dawg H2O as using hot water from a boiler or hydronic system, so it only fits homes with that kind of heat.
What size garage heater do I need?
It depends on the garage's size, insulation and door, and how warm you want it. A technician can measure the space and recommend a size. Modine's Hot Dawg gas models range from 30,000 to 125,000 Btu per hour.
How should an electric garage heater be wired?
Follow the manufacturer's installation instructions for the circuit and wire size, and have a licensed electrician do the work. For a plug-in portable heater, CPSC says to use a wall outlet, never a power strip.
Van Bremen's Heat & Air Installs Garage Heaters
Van Bremen's Heat & Air installs electric, gas and propane garage heaters, along with furnaces, boilers, heat pumps and ductless systems, from its office at 214 Stoystown Rd in Somerset. It serves Somerset, Fayette, Cambria and Westmoreland Counties and Morgantown, WV. The team assesses the garage layout, recommends the heater that fits, and installs it with proper ventilation and local code compliance. Learn more on the heating services page.
Visit Van Bremen's Heat & Air or call (814) 483-1735 today. Contact us for more information.
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