Definition — garage heating options
Gas unit heater: a ceiling-mounted forced-air unit heater fed by natural gas. Fastest to warm a cold garage; requires venting, a gas line, and TSSA-certified installation. Best for heavy-use workshops and detached garages.
Electric radiant garage heater: ceiling-mounted infrared or forced-air electric unit. Simpler installation (no gas), but expensive on electricity if used for long hours.
Ductless mini-split: an inverter mini-split provides both heat and cool, high efficiency, thermostat-controlled operation. Best for garages that double as home offices, gyms, or year-round workshops.
When each option fits
Occasional-use garage (weekend projects, storage): gas unit heater with a wall thermostat is the workhorse pick. Warms fast, holds temperature cheaply, doesn't care about summer heat.
Home gym or year-round workshop with real hours: ductless mini-split provides comfortable heat and cooling with individual thermostat control. The right choice for anyone using the space daily.
Detached garage or shop with no gas service: mini-split heat pump running from a subpanel — no gas run required.
- Occasional use → gas unit heater
- Daily use, year-round → ductless mini-split
- No gas available → ductless mini-split heat pump
Failure modes — garage HVAC safety rules
Ventilation matters: if the garage stores vehicles, chemicals, or fuel, adequate ventilation and a CO detector are non-negotiable. Ontario code requires specific separation between the garage and the living space; vent penetrations must not compromise it.
Combustion-air requirements: gas unit heaters draw combustion air from the room; a small tightly sealed garage may need a dedicated combustion-air intake. A TSSA-certified installer verifies this.
Never vent a garage HVAC unit into the attached house's supply ducts — that violates code and can carry vehicle exhaust into the living space.
The insulated garage door: an uninsulated garage door is the single largest heat-loss surface in any garage. Insulate the door before spending on HVAC — the ROI is better.
Proof — sizing a garage HVAC unit
A typical two-car GTA garage (450-500 sq ft, uninsulated ceiling above, insulated door) calls for roughly 30,000-45,000 BTU/h of heat to hold 15-18 °C on a design-cold day, or 12,000-18,000 BTU/h for a well-insulated attached garage.
For a ductless mini-split, that translates to a 12,000-18,000 BTU model. For a gas unit heater, a 40,000-50,000 BTU/h unit is common.
Action — Metroheat's garage HVAC quotes
We assess the garage envelope (door, ceiling, floor slab), the intended use, and the code separation from the attached living space before quoting. For gas unit heaters we handle TSSA paperwork and code-compliant venting; for mini-splits we design a proper line-set path.
Call (416) 283-5698 or visit /contact to book a consult.