Home / Services / Garage Heater Repair
Heating · Garage & ShopGarage Heater Repair
Garage heater repair is rarely about the heater's age: on a gas unit heater the fault is nearly always the igniter, the flame sensor, the pressure switch or the fan motor, fouled by dust. A diagnostic visit is $90–$150 and most repairs run $150–$800. Stop using the heater and call if you see soot on the cabinet, smell gas or exhaust, or find flame rolling out of the burner opening.
A garage is a harder place to live than a furnace room. Sawdust, drywall dust, road salt and paint overspray get pulled through the burner and across the flame sensor, and the heater sits cold and damp for more than half the year. The result is the same parts list as a gas furnace, failing sooner. A flame sensor coated in fine dust loses its signal and the burner drops out after a few seconds; a pressure switch hose packed with debris stops the heater before it tries to light.
The start-up sequence shows where it stopped. The thermostat calls, the venter motor starts, the pressure switch proves the vent is clear, the igniter glows or sparks, the gas valve opens, and the flame sensor confirms flame before the fan comes on. A heater that hums and never lights has stopped at the pressure switch or igniter, and one that lights and quits has a flame-sensing problem. One that runs for minutes and then trips off is overheating, usually from a failed fan motor; the no-light case is walked through in why a garage heater will not ignite.
A good share of the faults we find were installed, not developed. Unit heaters hung by the owner turn up with vent runs longer than the manual allows, single-wall vent that condenses and rusts through in a cold garage, and terminations too close to a window or the soffit. Clearances are the other pattern: shelving built later under the heater, or an overhead door that parks directly in front of the hot-air discharge when it is open. Gas piping and venting in Ontario is work for a TSSA-licensed technician under CSA B149.1, and we correct those faults before relighting anything.
The control wiring fails in ways indoor wiring does not. Thin thermostat cable stapled along a garage wall gets nicked by ladders, chewed by mice and corroded at the terminals by condensation. Battery thermostats quit in the cold because batteries lose capacity as the temperature drops, and a thermostat mounted beside the door or on an uninsulated outside wall reads the draft, not the room. We check for 24 volts at the heater with the thermostat calling before condemning any part on the heater itself.
Garage heater symptoms and what they point to
- The venter motor runs but the burner never lights: pressure switch, igniter or a blocked vent
- The burner lights and drops out within seconds: a dirty or failed flame sensor
- The heater runs, shuts off hot and restarts: a failed fan motor or a limit tripping on a dust-clogged heat exchanger
- Nothing happens at all: a thermostat, transformer or wiring fault
- Soot, a yellow lazy flame or an exhaust smell: shut the gas off at the heater and call before using it again
How it works
Tell us what the heater does after the thermostat calls: fan only, a click and nothing, lights then quits. Give us the make and model from the rating plate, and whether it runs on natural gas or propane.
We clean the burner and flame sensor, test the igniter, pressure switch and motors with a meter, and check gas pressure with the burner running. The vent run, clearances and gas piping are checked against the manual and the gas code on the same visit.
The failed part is replaced, the heater is cycled from the thermostat several times, and combustion is checked. If the heat exchanger is cracked or rusted through, the heater is not repairable and we quote garage heater installation instead.
Brands: We repair gas unit heaters and low-intensity infrared tube heaters of any make, on natural gas or propane.
Common questions
Why does my garage heater keep shutting off?
Either the flame sensor is losing the flame signal, which shuts it down in seconds, or the heater is overheating and tripping its limit after several minutes. Dust is behind both: it coats the sensor and it mats the heat exchanger and fan blade. The step-by-step version is in why a garage heater keeps shutting off.
Can I clean the flame sensor myself?
On a furnace many owners do. On a ceiling-hung unit heater it means working from a ladder inside a gas appliance, and the sensor is rarely the only dusty part. If you do it, shut off the power and gas first and use a fine abrasive pad, not sandpaper. If the heater still drops out afterwards, the burner, the ground connection or the gas pressure needs a technician.
My heater was installed by the previous owner. Should it be checked?
Yes, before the first cold week. We look at four things: vent material and length, the termination outside, clearances to stored items and the door, and the gas line, including its shut-off and sizing. A heater that has run for years can still be spilling exhaust into a garage attached to the house. Book the inspection with a repair visit request.
Is it worth repairing a 15-year-old garage heater?
Usually. Unit heaters are simple, parts are shared with furnaces, and a garage heater runs far fewer hours than a house furnace. Replace it when the heat exchanger has failed, when the cabinet and burner are heavily rusted from condensation, or when the repair costs more than half of a new unit on a heater past 15 years.
Do you repair infrared tube heaters and electric garage heaters?
Gas-fired tube heaters, yes: they share the igniter, pressure switch and flame-sensing parts of a unit heater, and the common faults are in why a radiant tube heater will not ignite. Electric fan-forced garage heaters are a different trade for anything on the supply circuit, which in Ontario is a Licensed Electrical Contractor's work under ESA rules.