What Makes Air Filters Get Dirty So Quickly?

Every responsible homeowner knows that regularly replacing dirty HVAC system air filters is important for maintaining clean air and a working unit. But for some, air filters seem to get dirty more often than they should, meaning more maintenance and replacements are needed. Here are a few of the most common causes of a dirty air filter, and how they can be avoided.

Pet Hair and Excess Dust 

While it's good that HVAC air filters catch particles like dust and pet hair before it gets recycled into the air, having too much of either in the home will lead to a dirty filter in no time. Air filters in homes with cats or dogs who shed excessively and homes with unused rooms or recent construction projects are especially at risk. Taking care of much of the hair and dust yourself can prevent excess strain on the air filter and the need for HVAC maintenance services. Vacuum as often as possible to collect hair and dust before it gets sucked into the filter, and brush particularly fuzzy pets at least once a week.

The Wrong Fan Setting

Having the thermostat's fan set to "on" instead of "auto" can be another reason for buildup on HVAC air filters. When it's set to "on," the fan blows continuously, even when it's not necessary to cool or heat the home. This setting means the filter must work non-stop to trap particles, almost guaranteeing it will get dirty more quickly. Sometimes, even fans set to "auto" can run too often if the weather outside is extremely hot or cold. This can be especially problematic in larger homes and commercial spaces, which need much more power to achieve the desired temperature.

The Filter Has a High MERV Rating

Inexpensive fiberglass filters allow some small particles through, making them less likely to clog too quickly. Filters with a higher Minimum Efficiency Reporting Value (MERV) rating will catch those smaller particles, which makes the air cleaner but means more frequent replacements and a heavier strain on the HVAC fan. An experienced HVAC technician can help you determine which filter is right for your system.

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