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How Often Should You Change Your AC Air Filters?

August 25, 2021

While people often know what air filters are within the AC system, not everyone knows all of the benefits that they bring.

Most AC owners will know the basic function of air filters – to clean the air.  However, most AC owners are not fully aware of the benefits that they bring and so often neglect to regularly change them.

What do air filters really do?

The air filters in your AC system serve 3 key purposes – System protection, Reduction of dust in the house and Indoor Air Quality improvements and we’ll look at these individually.

AC System Protection

A clean system is an efficient system, and the air filters prevent dust build up on the integral parts of your unit.  The filter acts as a barrier between the dust and debris and key components such as the Fan Blade, Motor and coils.

Without this barrier, severe dust build up can occur on these parts which can put extra strain on them potentially resulting in part or system failure.

Reduction of dust in the home

As air flows through your system and home, your air filters will trap and hold several grams of dust eliminating it from your home.  This will prevent the dust from flowing through your ductwork and back out into your home resulting in less dust in the air and on household surfaces.

Indoor Air Quality Improvement

The average person spends 90% of their time indoors where the concentration of pollutants are 2-5 times higher than outside.  Air filtration is very important especially for those who have severe allergies and sensitivities to certain contaminants, and the air filters in your system scrub these particles and contaminants from the air leaving you with improved indoor air quality and cleaner air.

How often should you change your air filters?

How long your filters will last depend on several factors including the type and quality of the filter, the air quality in your home and how much you use your system.

Fiberglass Filters – If you are using fiberglass filters, you should be changing them roughly every 30 days.

Pleated Filters – On average you should plan to change your pleated filters every 90 days.  With that being said, the longer the filter is in place the more dust and contaminants will build up which could affect the efficiency and effectiveness of your system so it’s always advisable to check your air filters every 30 days.

Other factors affecting the lifespan

In addition to the everyday build up of dust and contaminants, there are some other factors that can result in a longer or shorter lifespan of your filters.

Allergies & Asthma

If members of your household have allergies or asthma, they can be particularly sensitive to airborne particles and so it’s important to keep your filters working at optimum levels.  In this case you should look to change your filters every 4-6 weeks.


If you are a pet owner, your air filters can help reduce and eliminate odors.  Odors and pet hair can build up, especially as your pets sched, and so it’s best to change your filters every 2 months to maintain maximum efficiency.

Air Quality

How your system runs will be affected by both the indoor and outdoor air quality.  If you suffer from poor air quality either indoors or outdoors it is advisable to change your filters every 4-6 weeks.

Top Filter Tip

The best way to determine whether your filters need changing is to perform regular, proactive checks of your filters and inspect them to see if they are dirty or clogged.  Rule of thumb is that if you hold the filter up to the light, and can’t see light through it, then it’s time to replace the filter.

If you need help with selecting the correct filters for your system, reach out to our expert team for assistance.

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