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Why Bathroom Exhaust Fans Make Sense

Exhaust Fans

Beyond odor control, having well-functioning bathroom fans — that are sized and installed correctly — and using them regularly makes sense for other reasons as well, such as:

  • Avoiding mold growth and structural decay.Keeping bathroom humidity under control can help prevent mold growth and deterioration of your home's paint, drywall, wood trim and structural components.
  • Maintaining A/C efficiency.Removing excess moisture from the air also helps preserve your A/C's efficiency and keeps your operating costs in check.
  • Keeping chemicals out of your air supply.Good bathroom ventilation is essential to get rid of potentially-harmful chemical vapors released when you use bathroom cleaning products.


To ensure that you get the full benefit from your bathroom fans, make sure they meet the following criteria:

  • Ample capacity.The total fan capacity needed for average-size bathrooms – either one or multiple units – is one cubic foot per minute (CFM). Bathrooms larger than 100 square feet should have an additional 50 CFM capacity per tub, shower and toilet, and 100 CFM extra for jetted bathtubs.
  • Proper venting.Make sure your bathroom fan ducts go directly to the outdoors, not into a unfinished area like the attic where excess humidity can cause unnoticed mold growth and/or structural decay.
  • Efficient operation.To ensure efficiency, fans should be located right above a bathroom shower stall or bathtub. Additionally, the bathroom door should be undercut with at least one half-inch of clearance to let replacement air enter.
  • Ease of use.Ideally, exhaust fans need to stay running for 20 minutes minimum after every bathroom use. You can make sure this is accomplished by choosing fans with features like auto-start sensors, shut-off timers or built-in humidity sensors that start and stop the fan automatically in response to air moisture levels in the room.

To learn more about using bathroom exhaust fans effectively, contact us today at Valley Heating, Cooling, Electrical. You can also visit our website for in-depth information on most HVAC topics or just give us a call at (408) 868-5500.

Our goal is to help educate our customers in the South Bay Peninsula and Santa Cruz areas of California about energy and home comfort issues (specific to HVAC systems).

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