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Choose a torpedo heater for a garage or work area

By the Plain Prepper editors. Updated 2026-10-18.

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Quick answer

A torpedo heater is a forced air heater: a burner and a fan that blow hot air across a garage, shop or job site. Mr. Heater's forced air propane heaters come in 38,000, 60,000 and 125,000 BTU sizes that Mr. Heater says heat about 950, 1,500 and 3,125 square feet. They plug into a 110 volt outlet, run from a 20 lb or 40 lb propane tank, and Mr. Heater marks them not indoor-safe. Use one only in a ventilated work area, never in living or sleeping space, and keep battery CO alarms working.

What a torpedo heater is for

A torpedo heater, also sold as a forced air heater, pushes a lot of heat into a large open space fast. Mr. Heater lists its forced air propane heaters for construction sites, garages, workshops, agricultural buildings, remodeling jobs, industrial or commercial workspaces and emergencies. That last word does not mean a living room. Mr. Heater's spec list marks each of these models Indoor-safe: No.

In a winter outage, a torpedo heater can keep a detached shop or barn workable, thaw equipment, or warm a ventilated garage while you work in it. To heat the rooms you live and sleep in, look at heaters made and rated for indoor use, covered in our indoor propane heater guide and Big Buddy guide.

It needs electricity, even in an outage

The fan that makes a forced air heater work runs on household power. Mr. Heater says to plug the heater into a 110 volt outlet, then connect the included 10 ft hose and regulator to the propane tank. When the grid is down, that means power from a generator or another source.

If that source is a gas generator, run it outside only. CPSC says to never use portable generators inside homes or garages, even if doors and windows are open, and to keep them at least 20 feet from the home with the exhaust pointed away. Ready.gov gives the same 20 foot distance from windows, doors and attached garages. Our 5,000 watt generator guide covers sizing and cords.

Size by heat area and tank

Mr. Heater lists these sizes and tank needs:

• 38,000 BTU (MH38QFA): about 950 sq ft, up to 12 hours on a 20 lb tank, piezo ignition.
• 60,000 BTU (MH60QFAV): 30,000 to 60,000 BTU, about 1,500 sq ft, up to 14 hours on a 20 lb tank on low, continuous ignition.
• 125,000 BTU (MH125QFAV): 75,000 to 125,000 BTU, about 3,125 sq ft, up to 11 hours on a 40 lb tank on low, needs a 40 lb tank or larger.

Pick the smallest heater that covers your space. If your space is under about 950 sq ft, the smallest size covers it by Mr. Heater's rating, and the run times above show bigger heaters need bigger tanks. See the 20 lb tank guide and 100 lb tank guide for storage and refills.

Built-in safety, and what it does not cover

Mr. Heater lists factory-installed high temperature limit switches and thermoelectric safety valves on these heaters. Those help with overheating and flame-out. They do not remove carbon monoxide from the air or make the heater safe in a closed room.

Keep fresh air moving through the space while the heater runs, follow the ventilation rules in the manual that ships with the heater, and turn it off when you leave. USFA says to keep anything that can burn at least 3 feet from heat sources and to turn space heaters off when leaving the room or going to bed. A forced air heater blows hot air out of its front, so keep the outlet aimed away from fuel cans, sawdust, rags and the propane tank.

Put CO alarms where people are

CPSC says to install battery-operated CO alarms, or CO alarms with battery backup, on every level of the home and outside sleeping areas, and that interconnected alarms are best because when one sounds they all sound. Battery power matters in an outage, when plug-in alarms without backup go dark.

If an alarm sounds, shut the heater off and follow the alarm maker's instructions. Our carbon monoxide detector guide compares battery and backup models.

Before you buy

Check four things. First, the space: open, ventilated work areas only. Second, power: a 110 volt outlet or a generator run outside. Third, fuel: a 20 lb tank works for the 38,000 and 60,000 BTU sizes, while the 125,000 BTU model needs a 40 lb tank or larger. Fourth, noise: Mr. Heater says its QBT Technology makes these models 50% quieter than a standard propane heater, which helps in a small shop. Mr. Heater lists a 1 year limited warranty.

What to look for when you buy

Questions people ask

Can you use a torpedo heater indoors?

Not in living or sleeping space. Mr. Heater marks these forced air propane heaters not indoor-safe and lists them for job sites, garages, workshops and similar work areas. Keep fresh air moving and follow the manual.

Does a torpedo heater need electricity?

Yes. Mr. Heater says to plug these heaters into a 110 volt outlet. In an outage you need a generator or other power source, and CPSC says to run portable generators outside only, at least 20 feet from the home.

How long does a 20 lb tank last in a torpedo heater?

Mr. Heater lists up to 12 hours for the 38,000 BTU model and up to 14 hours on low for the 60,000 BTU model on a 20 lb tank.

What size torpedo heater for a garage?

Mr. Heater rates its 38,000 BTU model for about 950 sq ft and its 60,000 BTU model for about 1,500 sq ft. Measure the space and pick the smallest size that covers it.

Where should CO alarms go?

CPSC says on every level of the home and outside sleeping areas, battery-operated or with battery backup.

Sources

• 38,000 BTU Forced Air Propane Heater (mrheater.com), Mr. Heater
• 60,000 BTU Forced Air Propane Heater (mrheater.com), Mr. Heater
• 125,000 BTU Forced Air Propane Heater (mrheater.com), Mr. Heater
• Carbon Monoxide Information Center (cpsc.gov), U.S. Consumer Product Safety Commission
• Power Outages, Ready.gov (maker page: www.ready.gov/power-outages)
• Heating Fire Safety, U.S. Fire Administration (maker page: www.usfa.fema.gov/prevention/home-fires/prevent-fires/heating/)

Sources checked 2026-10-18.