When Should You Replace Your Air Filter with a MERV Rating?

The Minimum Efficiency Reporting Value (MERV) is a standard that evaluates the overall effectiveness of air filters. The average MERV 5-10 efficiency range will likely require filter changes in around two to three months. However, this range can vary depending on other factors and the filtering material. Air filters with a MERV 11 rating or higher usually take three to six months before being replaced.

The ideal is to change the MERV 13 filters every 30 or 90 days, depending on use and other factors. If your home is in an area with high humidity, is experiencing wildfires, has smokers, pets, or people with chronic allergies and asthma, you may need to replace the filter more often. A general rule of thumb for pleated air filters (such as those made by FilterBuy) is to change them every 90 days. As the filter traps more dirt, dust, and allergens from the air, the efficiency of the filter decreases.

It's important to note that there are high-efficiency filters that are designed to filter small particles of bacteria, mold, and mildew, but standard MERV 8-11 filters only block the largest particles of dust, dirt, and 26% of hair. The easiest thing to do is to periodically inspect the air filters for any signs of wear and tear, such as dark deposits, pet hair, and visible signs of other household irritants. If there are no smokers or pets in your house and your filter is filter 1, which is usually sold with a MERV rating of 4, you should be able to wait up to 90 days before changing it. Located at the upper end of residential air conditioning filters, the MERV 13 filter traps up to 90 percent of particles with a size of 3.0 to 10.0 microns and up to 50 percent of particles of 0.3 to 1.0 microns. Not only can doing so improve indoor air quality, but it also helps your HVAC unit run smoothly between filter changes. Any use can cause a certain amount of dirt to be trapped in the air filter; after all, that is its function. Air filters are usually made of spun fiberglass (the same that forms the insulation of the attic) or of pleated paper framed with cardboard for greater stability and rigidity. There is no strict guideline, but if the filter only shows a subtle layer of dirt under which the filter material is still visible, it means that the filter is working properly.

If someone in your family has mild or moderate allergies, you can use a better air filter or change it more often. In conclusion, it's recommended that you replace your home air filter every 3 months or 90 days. This will help keep your HVAC unit running smoothly and improve indoor air quality.