Air filters are essential electronic devices used in homes, offices, or any enclosed space to regulate temperature, collect dirt and allergens, and control humidity. The MERV rating is a scale that ranges from 1 to 20 and evaluates how well an air filter can remove particulates from the air. A filter with a higher MERV rating should last longer but can also restrict airflow in your home. When it comes to replacing your air filter, there is no one-size-fits-all answer.
It depends on the thickness of the filter, the MERV rating, the air quality in your home, and whether you have pets or smokers in your house. A good rule of thumb is to change 1- to 2-inch filters every three months, 4-inch filters every six months, and 5-inch filters every 12 months. If you can't see the filter material itself, it's time to replace it. For basic 1 to 3 air filters, brands generally recommend changing them every 30 to 90 days.
If someone in your family has mild to moderate allergies, you can use a better air filter or change it more often. Fiberglass filters should be replaced every 30 days, while pleated filters can last three to six months. The general consensus among HVAC professionals is that you should replace your furnace filter every 90 days or every three months. Thomas & Galbraith Heating, Cooling and Plumbing recommends changing filters less than 2 inches thick every 30 to 90 days, 3- or 4-inch filters every 6 to 9 months, and filters up to 6 inches thick once a year. If you want a hypoallergenic pet that doesn't lose hair, you might not have to replace the air filter as much. The air quality where you live can affect how often your oven filter should be changed.
A house that is occupied most of the time will require more frequent use of the air conditioning system and will need to replace the filter sooner compared to an empty house. If there are no smokers or pets in your home and your filter is the best-selling filter with a MERV rating of 4, you should be able to wait up to 90 days before changing it. In addition to filtering particulates filtered by MERV 8 and 11, MERV 13 can filter kitchen smoke, smog, and virus carriers. Thicker oven filters tend to last longer, providing greater filtration over time, so they usually cost more than 1 or 2 oven filters. Therefore, there is no clear answer as to how long the air filter can work efficiently before needing a replacement. However, following the guidelines mentioned above should help you determine when it's time for a new one.
