In general, most air filter manufacturers and HVAC companies recommend changing the air filter every 90 days or 3 months. This may vary depending on the location of your home, if you have pets, and the age of your system and equipment. Older systems often use fiberglass air filters, which should be replaced every 30 days. Newer systems typically use pleated filters, which should be replaced every 90 days.
If you have allergies, AC professionals generally recommend changing the filter every 45 days for maximum efficiency. A general rule of thumb for pleated air filters is to replace them every 90 days. As the filter traps more dirt, dust, and allergens from the air, its efficiency decreases. A one-inch oven filter should be changed every one to three months, while a three- to four-inch filter can last six to nine months.
A five- to six-inch coarse-grained filter can last nine to twelve months. By replacing your filters when needed, you can enjoy a heating and cooling system that performs better and clean air that is easy to breathe. When you remove the air filter from the air handling unit, hold it close to a light source to see if it is dirty or clogged. If you can't see the light through the filter, it's time to change it. More cycles mean more filter passes and opportunities to trap contaminants, so filters typically fill faster during periods of heavy use. If you have an asthmatic or allergic person at home, change the filter every 6 weeks for optimal indoor air quality.
If you have poor air quality outside or pets indoors, you'll need to replace your air filter more often. If there is a visible layer of dirt that covers most of the filter surface and that is thick enough to hide the filter material itself, it is a sign that the filter has been in the HVAC system for too long. Filter cabinets are used to place thicker filters while providing easy access to check or replace them as needed. Compared to other DIY home improvement projects, changing air filters is a quick and painless process that can be done in less than an hour. An HVAC professional can provide you with a recommendation on which filter would be best for your system and the needs of your home. Yes, changing the filter has several impacts on your HVAC system's ability to cool your home and overall air quality.
A dirty filter is often one of the main reasons for unnecessary service calls and can cause the system to be at risk of overheating and freezing.