The Homeowner’s Guide to Inspecting and Maintaining Makeup Air Units


If you have a high-powered, commercial-quality cooktop installed in your kitchen, chances are you also have a makeup air unit installed in your home. This device compensates for the amount of air being pushed out of your kitchen’s extractor and breathes fresh, room-temperature air in from outside. Makeup air units are typically automatic—unless you had yours recently installed, you may not even know you have one, but you’ll notice if it breaks down.

If your cooktop comes with a large extractor hood that sweeps out odors and contaminants from your home, your makeup air system is what’s responsible for replacing the lost air. Without it, your home would be depressurized and the kitchen hood would soon be unable to push the air out. The fumes would collect inside your house—creating a dangerous environment for you and your family.

Get Makeup Air Units Inspected Twice a Year

Fortunately, makeup air units are built to last, and if you take care to have yours regularly inspected you can catch any problematic developments before they seriously affect the device’s ability to function safely. Robert Tinsley of HPAC Engineering suggests biannual inspections for the best results. Have a certified HVAC technician examine the following:

  • Sensor—These devices are designed to automatically engage whenever your kitchen hood is pumping exhaust out of your home. If a faulty sensor causes the unit to delay in engaging or not engage at all, you’ll have to replace it. Testing the sensor is simple: just fire up your stovetop and wait for the system to engage.
  • Temperature Sensors—Just as makeup air units cannot function without a properly working kitchen sensor, they need correctly calibrated temperature sensors to determine how much they need to heat the air before pumping it into your home. If the temperature sensors do not work correctly, the system might pump in cold air, which will not counteract the pressure difference effectively.
  • Coils—Most modern makeup air units use a heating coil system to pump warm air into homes. Inspect these coils for corrosion, leaks or dirt. If the coil does not have a clear air path, gently wipe the obstruction off, starting from the output of the device. Coils should not have to be replaced very often; Thermolec coils benefit from a 20-year warranty.
  • Motor—The motor rarely needs anything more than cleaning and lubrication. If the motor does not feature grease fittings, then even lubrication is unnecessary. Clean the motor with a dry rag—never spray it with any solvent or liquid.

The filters, fan wheels, burners and orifices of the device generally only need to be cleaned. They will work perfectly as long as they are not covered or clogged with debris.

Clean Out Your Cooker Hood for Better Results

It can be helpful to think of your makeup air unit as just one part of an overall kitchen ventilation system. If the unit is working perfectly but the kitchen extractor hood is filled with gunk and debris, it stands to reason that you’ll experience some unexpected results.

Cooking hoods are simple to clean, requiring no more than elbow grease and a good cleaning solvent. Most contain some kind of filter that requires regular replacement—make sure that it isn’t obstructed, and consult Cleanipedia’s guide for more specifics on keeping it grease-free. With both these appliances in good shape, your home’s interior air pressure should remain in perfect equilibrium.

EP Sales maintains a large inventory of Thermolec and Greentek products and parts to service the needs of our customers.