Is my exhaust fan working?

| by Brian Wellnitz
Is my exhaust fan working?

If you've lived in your house for a decade or more, your ventilation fans have given you hundreds of hours of service. Like any mechanical device, the bathroom fan will eventually wear out. In the meantime, it may be slowing down and not providing adequate removal of moisture and odors.

The New York State Research and Development Authority's Homeowner's Guide to Ventilation offers a few simple tests.

The first test tells if your fan is working; the second test tells how well it’s working.

Test No. 1

From six inches away, squeeze a cloud of baby powder from its container toward the intake grille of an operating exhaust fan. If the fan is working properly, the powder should be drawn into the grille. If it goes to the center of the grille and is blown back into the room, then the fan is blocked; if the powder simply hangs in the air, the fan is not working.

Or turn on the fan and put a piece of tissue paper against the grille and let go. If it's working at all there will be enough air flow to hold up the tissue paper by itself.

Test No. 2

Find a cardboard box with an opening big enough to fit over the exhaust fan grille. If the fan is mounted in the wall, cut a hole slightly smaller than a credit card in the bottom of the box, or, if the fan is mounted on the ceiling, in the side of the box.

Using any kind of tape, attach a credit card inside the box over the hole. Make sure the card can swing back and forth in the box. Turn the fan on and put the box over the exhaust grille. If the fan is working, the credit card will swing into the box. 

The greater the air flow, the more the credit card will swing open. If it swings open 11⁄2 inches or more, the fan is moving at least 25 cubic feet of air per minute, which is a reasonable amount for a bathroom. If the card swings open less than 11⁄2 inches, you should consider repairing or replacing the exhaust fan. 

(Tip: use a pencil instead of a ruler to measure how far the card swings open, because a ruler will block the air flow.)

If your fan fails either test, it's time to look for a new fan. Replacing a bathroom fan in the ceiling or wall is a job best left up to a professional because it requires electrical and carpentry skills.

About Broan: With Broan, it’s all about powerful, well-designed home ventilation products. You can count on Broan to combine quality, and engineering excellence to create elegant products that get the job done, effectively and consistently, in addition to complementing your home’s décor.

Topics: Bathroom, Indoor Air Quality, Kitchen, Ventilation

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