Types of Air Conditioner filters and how they work?

A carefully chosen AC filter is undoubtedly one of the most crucial needs. Generally, the AC filter which is often seen just a stiff cloth or a cardboard piece acts as a defensive guard against the harmful foreign and contaminated particles in the room’s indoor environment.

Despite being so important for the main AC unit, unfortunately, these AC filters are not given attention and are mostly overlooked during the time of purchase. If you too are ignoring paying attention to your AC filters, then it is time for a change.

Let us take you through the different types of AC filters available in the market and their working to make you understand their need and importance.


Different types of AC filters:

With the technical advancement, even the AC filters have improved in their design, working, operations, and efficiency.

Fiberglass Filters:

These are the most common type of AC filters used. They are also commonly known as throwaway filters as they are generally designed for single use only and last for a maximum of 30-days only. These are not that effective when used for the second time.

They are mostly considered safe and are also affordable for a buy. It is because of their affordable price that is a popular choice amongst the users.

This type of filter works the most effective in removing just the large dust or contaminated particles from the surrounding air. However, the filter efficiency to remove the smaller particles is somehow limited and as a result, they offer little protection to the user’s health. They are also not suitable for people with asthma or any kind of allergy.


Several strands of fibreglass are spread over a frame which then acts as a barrier to prevent the harmful contaminants and dust particles from entering the indoor surroundings.

These filters can easily be found at any departmental or retail store without any hassles. However, they generally have a MERV rating between 1 and 4.


HEPA Filters:

These are some of the most popular and trending filters with maximum efficiency rate. These filters are capable of removing nearly 99.97% of contaminations and germs from the surrounding air to offer healthy and pure air.

A true HEPA filter is capable of filtering 0.3 microns or greater particles. Its working makes it stand distinguished from the other filters and to maintain its efficiency. These filters come with 17-20 MERV which can even trap and remove bacteria, germs, minute tobacco particles from the air without any hassles.

The only concerns associated with this filter type are its high cost and the need of having a professional installation for its effective and stable working. Also, they cause no harm to people with allergies or any type of illness.


The working of the HEPA filter can be categorized into 3 main stages.

In the very first stage, the filter act upon the large and big particles. As the flowing liquid changes its flow direction, these big particles remain in the straight line, thereby hit the filter and gets trapped.

The second stage of filtering, or also known as diffusion, filter the smallest dust particles. Since the small particles flow the liquid in the same direction, they are caught by the fiber when they traverse the flowing liquid stream.

Following the second stage, comes the last stage of direct interception which mainly focuses on medium-sized particles. Such particles keep following the stream until it bends through the available fiber spaces for filtration.


Pleated Filters:

These filters are quite similar to the fibreglass filters and are popularly known as surface filters. They make use of polyester fabric for filtration. In some of the pleated filters, some other cloth pieces are also used instead of polyester which doesn’t compromise with the filtration process.

These filters are mainly used for blocking the flow of dust particles in the room. The cloth piece is used in the shape of an accordion to have minimal resistance for the airflow. The filter offers a maximum surface area for filtration and is also long-lasting.

In simple words, the working of pleated filters ensures depth and detailed filtration for the removal of greater sediment particles. The larger surface area keeps it going for the maximum time without the need for much maintenance.

The biggest drawback of this filter type is that they work the best with uniform size particles. For example – if all the surrounding particles are of 3-micron size, then a pleated filter of 3-micron would do complete justice for filtering them and will also last for longer without causing any hassles.


This thin filter works on the principle of capturing all the sediment particles from the surroundings. Thanks to the wide surface area, a good number of particles can easily be collected using this filter.

As soon as the large sediment particles come in contact with the surface area of this filter, they get captured on the surface. However, it is not that effective for very small particles but still can be trusted for effective filtering.

This filter is used until the entire surface gets covered with particles after which it is disposed of. However, if you have invested in a high-quality pleated filter, then it can be reused after proper cleaning and maintenance.


Washable or reusable Filters:

Last but not least, we have washable or reusable filters. Well, as the name suggests, these filters are the ones that can be reused after their proper hygienic cleaning and maintenance. These are generally cloth-based filters that can easily be washed and used again and again as per the need.

Because of their reusability, these filters are quite cheaper than the other filters. However, these are designed for low-intensity usage and are not much suitable for very polluted surroundings and environments. Generally, most of the washable filters have their MERV value between 1 and 4.

To ensure that these filters can be reused again, special care should be taken while washing and cleaning them. If they get damaged even slightly, then they cannot be used again. Also, they should be completely dried before reusing them else there are high chances of fungi growth that can damage the appliance.


The working of washable filters is pretty simple. These filters take the polluted air from the surroundings which passes through the filter. As soon as the air comes in contact with the filter, the heavy and big dust and contaminated particles are blocked from passing through.

Since the reusable filters have low MERV, they are not capable to work effectively against the small dust particles and as a result, cannot remove them. They are only effective against the big particles.

Once, the filter is filled with particles, it is removed, cleaned, and then re-inserted in the AC for use. However, it should be taken care that the filter should be completely dried before being reused unless it can damage your AC.


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Final Thoughts:

It is quite important to choose the right filter for being sure of getting clean and pure air. Now, when you are aware of the different types of AC filters available in the market, it would get a little easier for you to choose between them.

The importance of inhaling clean air should not be taken for granted and thus you shouldn’t make any compromises when choosing the best and suitable AC filters. Be very sure to check all the essential parameters and aspects of the filter before making any final decision and enjoy clean air!

Kindly let us know which of these different types of filters do you liked the most? Also, if you have any doubts or concerns, then please do comment below to get our detailed assistance.


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