Every time a kitchen exhaust hood runs, it pulls a large amount of air out of the building. The make-up air unit brings that air back in, and in Calgary it has to heat it first, sometimes from well below zero. When the make-up air unit isn't working, the kitchen gets cold, doors are hard to open, and the hood can't pull smoke and grease out properly.
Make-up air units are easy to forget because they sit on the roof. A maintenance visit before winter, and again before summer, prevents most of the calls we get in the middle of a cold snap.
What a maintenance visit should cover
Air side
- Replace or clean the filters. Clogged filters starve the unit of air.
- Check the belt for wear and tension, and the pulleys for alignment.
- Check the blower and motor bearings for noise and wear.
- Check that the intake hood and screens are clear of debris, snow and bird nests.
Heating side
- Inspect the burner and clean it if needed.
- Check the igniter and flame sensor.
- Test the safety controls, including the high-limit and airflow switches, so the unit shuts down safely if something goes wrong.
- Confirm the gas pressure and that the unit heats to its set temperature.
- Look for gas line corrosion, loose fittings and damaged supports.
Controls and the hood link
- Confirm the make-up air unit starts when the exhaust hood starts. If the hood runs without make-up air, the building goes into negative pressure.
- Check the thermostat or discharge air setting and the control wiring.
- Check the motorized damper opens and closes fully.
Signs it needs attention now
- The kitchen is cold when the hood is on, or the unit blows cold air in winter. See make-up air unit not heating.
- Doors whistle, slam or are hard to open, or the front-of-house smells like the kitchen. These are classic signs of negative pressure.
- Smoke or steam hangs under the hood instead of being pulled out.
- Squealing belts, rumbling bearings or the unit tripping off repeatedly.
How often
For most restaurants, twice a year is the minimum: once in the fall before heating season and once in the spring. Busy kitchens with heavy grease loads, or units that run long hours, may need filters changed more often. Pairing the visit with your exhaust hood and rooftop HVAC maintenance keeps everything working together.
Keep the kitchen running
YYC Mechanical services and repairs make-up air units and exhaust systems for restaurants and commercial kitchens across Calgary and nearby towns, including Engineered Air, CaptiveAire and other common brands. Planned maintenance is available, and our emergency line is open 24/7.