Air Conditioning Filters

 Types of Air Filters

The filter of an air conditioner should be changed ideally once in every month. Even if that is not possible due to a busy schedule, you should at least try doing so once in every three months. The frequency of filter change is also determined by the amount of your AC usage. The rule is that you should not allow dirt and dust to sit and settle on your filtration mesh. This will not only reduce your comfort by clogging the flow of air but also increase your power bills. Your machine will work hard you keep up the level of cooling which will lead to increase in power consumption. Moreover dirt filters are also bad for evaporator coils and the compressor. As very little room air will be able to reach the coils for cooling a marginal quantity of heat will be dumped. The refrigerant in the coil will not get enough heat to get evaporated. This will lead to icy coils. The refrigerant will move back to the compressor in partially liquid form which can cause harm to the compressing unit.

Maintaining and changing the filters play a key role to enable the AC perform at the peak of its efficiency. Here we will take a look at different types of air conditioning filters-

 Mechanical Air Filters

These are most commonly found filters in homes. These have meshes made of synthetic fibers that can trap small particles like debris and dust very well. The charcoal filters also use mechanical means to filter air. Fiberglass filters are commonly found in AC units. These are also classified as mechanical filters. The come generally in two size- 1 and 2 inches. The measurement refers to the thick mesh of the fiberglass thread that is used to make the filter. These are cheapest among the various categories of filters. They only need to be replaced and cannot be reused with washing. They are not very effective as the adhesive coating and mesh that filter the air particles are often damaged by cleaning.

 HEPA Filters

These are known as High efficiency particulate arrestance filters. These can filtrate very fine particles that are moving with air. The U.S. Department of Energy (DOE) and its contractors use HEPA filters that meet DOE standard STD-3020-97. These filters can trap 99.97% of particles in the diameter range of 0.3 to 0.4 micrometers. This range is narrower than the cross-section of human hair. The fibers of these filters are arranged randomly and have creases or pleats.

 Pleated Air Filters

These are also a category of filter that are said to remove almost 35 to 40% of the air pollutants in the home. These are more effective than mechanical filters as they are more closely weaved. They contain more fiber per square inch as compared to disposable fiberglass filters. The denser weave enable them to trap more dust.

 Electronic Air Filters

These are most expensive ones among the various types of filters. They are so effective that they can even trap smoke, mold spores. These filters use electricity to attack the molecules of dust and smoke or molds. The can also remove pet odors. These filters also come in 2 sizes. These filters can last for 6 months. These also have an additional pre-filtration layer that traps bigger particles. The electronic layer is used for smaller ones. There are some controversies about these filters. It is said that these filters have certain ionizing properties which produce dangerous ozone substances.

The electrostatic filters also are part of this category. They have unique way of working. They charge the air with static energy that attracts dust and debris. They need to be changed once in every 3 months. They are often called allergy-free filters.

 Washable air filters

These filters are found in industrial HVACs where lots of dirt and debris clog the duct day in and day out. They need to be cleaned and can be reused after doing so.


Filters are also classified by their MERV rating. A filter with a MERV rate of 7 is best for trapping large particles. If you have pets in your homes go for MERV rating of 8. If you or any member of your family is suffering of allergies or respiratory problems MERV rate of 11 will work best for filtering the air of all contaminants.


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