Make-Up Air Units: What are they adding to your shop environment?

Look into the peephole for your burner. If the flame is blue and tight, chances are good that your unit is operating with proper combustion and that your airflow is correct. If the flame is yellow and large, the makeup air unit could be releasing excessive levels of carbon monoxide into your shop environment. Excessive carbon monoxide levels can cause inexplicable headaches, nausea, extreme drowsiness or unconsciousness.

Two possible causes for a improper combustion are: 1. improper airflow or 2. improper gas flow. Improper airflow can be caused by dirty filters, worn belts or something overlooked during start-up. Improper gas flow can be caused by faulty components in your gas train or improper pressure from the gas supplier. Any of the above can load your shop environment with excessive levels of carbon monoxide.

There are a couple ways to remedy improper airflow. Worn belts should be replaced with a new matched set. Another approach, favored by the seasoned techs, is to either increase or decrease the pulley size on the motor (if this issue was overlooked at initial start-up.) A larger pully speeds up the fan if you don't have enough air movement. A smaller one slows down the fan unit if your air movement is excessive. One good indicator of too much "oomph" in your fan is booth ceiling filters taking a real beating and "pouching" out. Bear in mind, both problems are best left to professionals that are trained in calibrating equipment to factory specifications.

Its good to know what your burner is doing before your local OSHA folks look at it. A healthy shop environment is paramount. Use your eyes and nose - a properly adjusted make up air unit will leave very little, if any, noticeable odor in your shop environment. A strong acrid odor (e.g. the smell of car exhaust) or a large, lazy, yellow flame should send up a red flag to have your unit checked out immediately.

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