AIR FILTRATION

There are four basic types of air cleaners. The first air filter is the old style fiberglass filter. The second type of filter is a pleated media filter that looks like it is made from felt. Most of these filters look white. The third type of filter is an electrostatic filter. The forth type of filter is an electronic air cleaner.

The old style fiberglass filter does not filter air as well as the other filters. It does not restrict the air flow as much and if you have marginal air flow it may be the filter you are stuck with unless you want to install an electronic air cleaner.

Standard filter in track	Standard Filter

Pleated media filters filter air much better that the old style fiberglass air filters. If you have marginal air flow in the duct system this type of filter may cause the evaporator coil for the air conditioner to freeze up in the summer and it may also cause the temperature rise for the furnace to be too high. (See furnace inspection) Two high a temperature rise can damage the furnace.

Example of higher efficiency pleated filter

The electrostatic air cleaner uses the velocity of the air to create an electrostatic charge on the dust particles. The charge on the dust particle is attracted to the filter which has the opposite charge. There is a tendency for these filters to have a relatively high pressure drop which also restricts the air flow. If you have plenty of air flow in the duct system these air filters work good.

The forth type of air filter or cleaner is an electronic air cleaner. This filter charges the dust particles with one type of charge and the filter has the opposite charge on plates as the air goes by. The opposite charges attract and the dust particle attaches itself to the charged plate. Since this air cleaner works with voltages as high as 5000 to 7000 volts some experts think that ozone can be created under some conditions. This type of air cleaner requires more service and the cells have to be washed every 30 to 60 days. This type of air cleaner removes smaller particles of dust and does not restrict the air flow in the duct system.

Electronic air cleaner installed in return air ductwork	Electronic air cleaner cell	Electronic air cleaner cell

Another type of air filter is made from activated charcoal. This type of filter removes organic compounds such as benzene and formaldehyde. This type of filter is used in addition to air filters to remove dust.

Ultraviolet lights are used to reduce mold spores in the air.