Changing your air filter regularly is one of the best and simplest ways you can keep your HVAC system running properly and, most likely, extend its longevity. The longer you go without replacing the air filter in your HVAC unit, the more dust, dirt and allergens can accumulate and clog things up, causing a whole host of problems, such as malfunctions, equipment damage, reduced air flow (causing fans to work improperly or stop working entirely), duct build-up or releasing contaminants back into the air. 

So, how often should you change your HVAC filter? On average, you should plan on changing your HVAC filter every 30 days if it is a less expensive fiberglass filter. The higher-end pleated filters can last from 90 days up to as long as 6 months. 

However, keep in mind that there are several things that can accelerate these timelines. For instance, for children or anyone with allergies or asthma, you should change your HVAC air filters more regularly. In this case, six weeks is a good rule of thumb to help keep things cleaner and everyone healthier. If you are dealing with pets, you should change a good filter at least every two months and, if shedding is a factor, even more often at the change of seasons when shedding is worse. 

The good news is that if you are located in a mild climate where your HVAC unit doesn’t run very often, your filter could last an entire season or longer. Unfortunately, for the most part, that is often not the case in Florida. If you are like most of us here, your HVAC system runs nearly constantly, requiring an HVAC air filter change every few weeks, especially if we are talking about the fiberglass kind.

Finally, you need to consider size. The smaller the building, the less air needs to be pumped through your filter for a temperature adjustment, so filter changes would be required less often. This is not necessarily the case, however, if your HVAC unit is a small one because your house or building is small.

Bottom line is that you should plan to check your HVAC air filter once a month. If it looks dirty, change it.