How Air conditioning filters work.

Air conditioning filters

How Air conditioning filters work.

Air conditioning filters are required to trap small particles that are suspended in the air. Fundamentally they are simply a medium with small holes that allow air to pass through but not particles.

A home central air conditioning system includes two types of air filters. The first are the flat panel variety which are installed behind the return air grills, and the second is the whole house filter that is usually installed in the air handler.

The flat panel filters are easy to understand. Each one simply consists of a rigid flat sheet of compressed, meshed together fibers. As the air passes through the spaces between the fibers, particles, dust, pollen, dander, fibers and other larger particles, bump into the fibers and are stopped from entering the return air duct.

Whole house filters also consist of sheets of meshed fibers; however, the spaces between the fibers are smaller, and the sheets  are wider. In order to be able to fit a wide sheet into a small space, the sheet is folded. The resulting concertina looking structure provides a greater surface area to trap particles, while at the same time providing sufficient opportunity for the air to pass through.

Standard central air conditioners usually only accommodate whole house filters that are the flat sheet type or a pleated type which only has a small number of pleats, the latter being only slightly more effective than the flat sheet type.

Particles are trapped in the fiber mesh when they either bump into the fibers or hook onto them as they attempt to pass between them with the air movement. The greater the number of fibers and the smaller the holes between them, plus the extent of the surface are of the mesh, determines the filter’s efficiency rating, or MERV rating. (More info about MERV).

Once air conditioning filters reaches a high MERV rating, they are referred to as HEPA filters. HEPA filters do not allow sufficient air to pass through them for the proper functioning of the air conditioning system. When this happens, the problem is overcome by removing the filter from the air handler and installing it inside a by-pass duct. Part of the main air flow passing through the return air duct is then diverted into the by-pass where it is able to move slowly through the HEPA filter before being reintroduced to the main air flow in the return air duct. Eventually, all of the air has an opportunity to move through the by-pass and be cleaned while the air conditioner can operate much more efficiently without having to work against any air filter resistance.

Home air filters

Continue reading my Air Conditioning Filters including Best features, What makes them green, FAQs, plus Tips and Tricks. Please visit my Green Store and support Switch it Green, Switch it Forward.

Please see our other review posts for this living green product: 

Best features home air filters

What makes a home air filter green

Air conditioning filter Frequently Asked Questions

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