How Often Should You Change Your Air Filter?

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. The only way to be sure how often the air filter needs to be changed is to perform a visual inspection of the filter every month. After a few months, you'll have an idea of how quickly it gets dirty.

You'll need to re-evaluate if you're having a new pet or if the outside air quality has been poor. 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 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, its efficiency decreases.

Depending on your lifestyle and the type of oven filter you choose, you may want to change it more often. A number of factors must be considered when deciding how often an oven filter should be changed, and many filter manufacturers recommend how often their product should be replaced. Air filters should be changed every 90 days on average. An air conditioning filter will only last one to three months on average.

Which means you should keep track of the date you installed them. If you wait too long to change the filter, indoor air quality will be affected. Let's explore each of these factors in more detail. The most important factor is how often the system is running.

The filter collects dust and dirt only when the system is operating. The more it works, the faster the filter will pick up dirt. During an extremely cold winter in Minnesota, an oven filter will need to be changed more frequently than during a mild Missouri winter. On the other hand, you'll need to change your filter more often during a hot, humid Missouri summer than during the Minnesota summer.

Remember that a filter also gets dirty during AC mode. Do you find pet hair in your oven filter? The hair fibers of dogs, cats, rabbits and other mammals are large compared to the dust and dirt normally trapped by the filter. That means they clog the filter and block the air flow quite quickly. The more important clean air is, the more often the filter must be cleaned or changed.

A coarse-fluid filter, MERV 11 or higher, or an electronic air purifier is the best choice when someone in the household has asthma, severe allergies, or respiratory problems for any reason. The air will be cleaner than if you use a basic fiberglass air filter. You may also want to consider an air purifier for your system. Cheap fiberglass filters need to be changed less frequently than pleated filters.

Some sites do it exactly the other way around, stating that thicker filters can last longer between changes - but that goes against the design of the filters. Coarse-media filters trap more and smaller dust particles, so they obviously clog up faster than fine fiberglass filters which don't trap as much dirt and debris and don't clog as quickly. The good news is that some of those filters can be cleaned with a nylon brush and placed back in the oven or air controller instead of replacing them - but cleaning should be done outside or in a garage to keep dust and dirt out of your home and after two or three cleanings won't remove enough deeply embedded dirt and debris. In larger homes, more air flows through the filter than in smaller houses because air transports dust, pet hair, and other debris - so the filter will get dirty more quickly in a system that works in a large house.

Some people wonder what we mean by continuous fan mode and why an owner would use it - there must be a setting on the thermostat such as Automatic and Fan options where in automatic mode, the fan works only when the system is heating or conditioning the home while in fan mode it works all the time until you turn it off - running the fan consumes electricity so you'll see an increase in your electricity bill but it helps to balance temperatures in your home and if you have a basement you can draw cold air from there to help cool floors above - however humidity makes you uncomfortable in summer so you'll need to lower thermostat setting which causes AC to run more frequently leading to higher electricity costs so we don't recommend continuous fan mode as standard operating procedure. So how often do filters need to be changed? This question gets to the heart of the matter - follow these steps to find out when: 1) Perform a visual inspection of your filter every month; 2) Re-evaluate if you're having a new pet or if outside air quality has been poor; 3) Change pleated air filters every 90 days; 4) Consider changing other types of oven filters depending on lifestyle; 5) Change AC filters every one to three months; 6) Consider using an electronic air purifier for better indoor air quality; 7) Clean fiberglass filters with a nylon brush instead of replacing them; 8) Change fiberglass filters after two or three cleanings; 9) Don't use continuous fan mode as standard operating procedure.