In general, most air filters should be changed 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. Pleated air filters are more expensive initially, but they are also more efficient at trapping particles and can last up to 90 days, depending on use. The ideal is to change your air filter every three months, however, there are certain factors to consider when determining when to replace an old filter.
A general rule of thumb for pleated air filters (such as those manufactured by FilterBuy) is to replace the filter every 90 days. As the filter traps more dirt, dust and allergens from the air, the efficiency of the filter decreases. Numerous contaminants and debris, including excess dust, can cause air filters to clog and reduce air circulation throughout the home. The more folds an air filter has, the better the chances of removing contaminants from the indoor air.
Consider replacing air filters after a major home renovation to keep the air clean and reduce the chances of costly maintenance repairs later on. When you remove the air filter from the air handling unit, if you hold it close to a light source, you can see if the filter is dirty or clogged; if you can't see the light through the filter, it's definitely time to change it. Fiberglass filters have a lower price; however, they will need to be replaced more frequently (usually every 30 days). To ensure that only clean air comes out of your HVAC system, replace the air filter before it becomes clogged so that you can breathe better.
However, many homeowners are unaware of how often air filters need to be replaced, leaving their system vulnerable to damage. Even so, the filter expiration date should be the maximum date until which you keep that particular filter. On the other hand, if you use your HVAC system almost constantly, you'll need to change the filter every few weeks (especially if you use fiberglass filters). Changing the air filter will help keep parts of the air conditioner clean and prevent wear and tear.
The longer the filter is in place, the more dirt, dust and allergens are trapped, clogging the filter and decreasing its efficiency. Air filters help clean the air in a heating and air conditioning system by removing unwanted debris. 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. If you live alone without pets and with good surrounding outdoor air quality, then following manufacturer's recommendations should work well for you.
If you live in a mild climate and only use your AC or heater for a few hours a day, a filter could last up to an entire year. If you have an asthmatic or allergic person at home, change the filter every 6 weeks to ensure that indoor air quality is at its best.