How Frequently Should You Change Your Air Filter?

13 August 2015
 Categories: , Blog


One of the most critical things to do when it comes to HVAC maintenance is also the simplest. Changing your air filter not only ensures that your HVAC system performs at its best, but it also helps you maintain your home's indoor air quality. But when should you change your air filter and how often? The answers may surprise you.

Every Three Months or Once a Month?

Conventional wisdom seems to be split on how often air filters should be changed. Some experts recommend that you should change your air filter at least every three months, while others recommend changing the filter on a monthly basis.

Which interval is best? That depends on a wide variety of factors, including the type and size of HVAC system installed in your home, the type of filter you're using and your home's current indoor air quality. For instance, a particularly dusty indoor environment is likely to wear out air filters faster than an environment with relatively clean air from the start.

Visual inspections are always a good way of determining when you should have your air filter changed. If your air filter quickly accumulates dust, fibers and other airborne pollutants, then you should have it changed on a monthly basis. Otherwise, it's best to stick to a three-month rotation.

How Air Filter Quality Affects Change Intervals

The quality of your HVAC air filter also plays a role in how often you'll need to change it. In most cases, air filters with higher MERV (Minimum Efficiency Reporting Value) ratings need to be replaced less frequently than those with lower MERV ratings.

This means that a simple fiberglass air filter with a MERV rating of 3 may need to be changed on a monthly basis. Meanwhile, a pleated air filter rated at MERV 11 may need less frequent changes, depending on the HVAC system and indoor air environment.

When in Doubt, Follow Manufacturer Recommendations

To ensure maximum system life, HVAC manufacturers may offer their own recommendations on when you should change your HVAC system's air filters. These recommendations can be found in your HVAC system owner's manual. If you're unsure of how often you should change your air filter, you can refer to these recommendations for greater peace of mind. If you're really stuck, contact a contractor like Mike Kearsley's All Service.

According to the U.S. Environmental Protection Agency, indoor air pollutants rank among the top five environmental risks to public health. Knowing when to change your air filter helps you keep your home's indoor air cleaner and healthier.