Custom Air Filters - Are They Necessary?
What are they?
They are a type of air filter that is used in an air conditioner or a furnace. Unlike the air filters that you can purchase at your local store, these air filters are made to an exact length, width and depth. The size that the filters are made too depends on where and how the filter is to be used.
Why are they needed?
Working in the air conditioning & heating industry for many years I can say one thing the industry never did was to standard filter sizes. Air conditioning manufacturers decide on the filter size based on the final size of the unit, So there are literally hundreds of different sizes of air filters. Then there are the filter-back return air grills, those are the big louvered grills in the walls that suck the air in. Return air grills can be made to any size, which means hundreds more filter sizes.
Who can benefit from a custom made filter?
Considering there are hundreds of different filter sizes, and most home stores carry less then ten different sizes. A lot of people. Most people just purchase a filter size that's "close" to their required size. So they get it home and either they have squeeze and bend it to get it in, or it slide right in because it's too small! In both situations you are causing yourself problems. Because air is funny, if it has a choice between resistance and no resistance, it chooses no resistance every time! This means if you air filter is not properly sized and sealed, all the air and pollution will just go around it, and avoid filtration completely. To make matters worse, some people purchase a high efficiency air filters, to get better filtration. But higher efficiency, usually means greater resistance, which only compounds the problem.
What are the results of poor air filtration?
When airborne particle are not trapped by your air filter they are able to enter your air conditiong system. Once inside your AC these organic and inorganic contaminants find the perfect wet dirty environment to thrive and multiply. Some very dangerous pathogens have been known to thrive in these conditions, such as Legionella pneumophila, E. coli and Bacillus subtilis. Once spores germinate and growth occurs in air conditioning unit or anywhere inside the building, new spores may be generated and appear in the return air.
What types are available?
Like the furnace filters you find at your local home store, there are many different types available. The first thing you should decide when you are going to order custom air filters is efficiency. Efficiency is how effective the air filter is at removing particles from your air. A common measure of efficiency of furnace air filters is called M.E.R.V.( minimum efficiency reporting value). The higher the M.E.R.V. rating, the more efficient the air filter. Keep in mind the higher the efficiency, the greater the resistance, so make sure you system can handle the extra load.
Filter media in different shapes as well, you have your flat type filter media, like fiberglass and polyester. Another type of media is the extended surface pleated type material. Air filtration media uses either mechanical or electrostatic methods of filtration. The electrostatic method offers the benefit of lower resistance to air flow.
One of the most important factors, and often overlooked, is an air filters ability to make a positive seal within the system it is being place. Without a tight seal, the pollutants will find a way to get around the air filter and avoid filtration. There are a few filters on the market that have a gasket on the filter to prevent air bypass. If you have to use duct tape to seal the filter so the air can't go around it, then do so.
