So What are the Different Types of Filters Available and What are the Pros and Cons of Each
The standard fiberglass filter. Generally this comes in one or two inch thickness. This filter is considered a Filter and is really not suitable for a system with air conditioning. It is inexpensive and widely available, but a homeowner that uses this type of filter will need to have their cooling coil pulled and cleaned approximately every two or three years because of the inefficiency. This can actually be one of the most costly filters you can use. Not only do you have to service the system much more, but the additional inefficiency of the equipment costs you dearly on your electric bill.
Probably the least efficient filter you can use is the aluminum mesh washable filter. This filter allows the dirt and dust particles to slide off the aluminum mesh surface and is even less efficient than a fiberglass filter. If you use this type of filter you will need to have your cooling coil pulled and cleaned every year. Some people use these filters because they are not disposable and they don’t have to buy new filters every month, but it is costing them much more in inefficiency in the operation of their cooling equipment.
The standard polyester filter. Generally this comes in one or two inch thicknesses. This filter is an upgrade from the fiberglass filter, but is still pretty inefficient. With this type of filter even if you change it regularly you will usually need to have your coil pulled and cleaned about every five years. These filters are only slightly more expensive than the fiberglass but are several times more efficient.
A polyester pleated type filter comes in one, two, or four inch thicknesses. These filters are made of a much denser material which catches smaller particles. The material used is the same for the different thickness filters it just gives added surface area so that it will hold more dirt and you have to change it less often. The efficiency is slightly higher for the thicker ones because the increased surface area allows the air to pass across it slower which makes it a little more efficient. These filters are more restrictive to airflow and you need to be careful that you have a large enough filter to allow for the amount of air that you need to move through it. If you have a restricted return space with too small a filter you can cause freeze up problems or sweating problems in your air conditioning system.
The next step is the HEPA type high density pleated filters. These filters are generally four or five inches thick and provide a much denser material than the standard pleated filter. They increase the surface area by providing more pleats so that there is not too much restriction. These filters are very good and generally are rated at about a MERV 10. These are cartridge type filters and generally need to be replaced every six months to one year depending on the home. Another advantage to these filters is that they get more efficient as they get dirty. The dirt build up tightens up the pore spacing in the material and makes it catch more of the smaller particles. These units generally have to be installed by an air conditioning professional and do not just slip into the normal filter slot.
The April-Aire high efficiency air cleaner type filter is a high density pleated filter that comes in a completed unit. The media has a MERV rating of 10 and because it has over 76 sq. ft. of surface area it can generally go for about a year between changes. This is a very good filter with no moving parts and nothing to go wrong. Like the cartridge type media filters above, this filter also gets more efficient as it gets dirtier and has to be professionally installed.
The electronic filter which is a filter generally about five inches thick is run with an electric current. This filter electronically creates a charged ion field which the particles pass through. In this field they are electrically charged and then they pass through to a collector cell which has the opposite electrical charge. The particles are then attracted and collected on the plates of the collector cell. This technology has been around for decades. These filters can be very efficient because they capture even the smallest of particles. The problem is that in normal operation in your home the collector cells need to be cleaned every three to four weeks in order for them to stay efficient. As the dirt and dust build up on the collector cells the efficiency decreases drastically. The other problem with this type of filter is that in order to create the proper ion field and collector field they have to produce between 6,000 to 9,000 volts. Because of the high voltage and the sensitivity of the cells these units tend to be very fragile and need service quite often. Plus if the unit is not working then the only filter it uses is a small ¼ inch thick aluminum mesh filter which is almost like having no filter at all. Because of the maintenance and the mechanical problems with these units I do not recommend them.
The Trane CleanEffects filter is a combination of High Efficiency Media type filter and Electronic air cleaner built into one. The media prefilter catches the larger particles and then the Electronic part catches the small particles. The prefilter keeps the electronic part from loading up with the large dust and makes it to where it doesn’t have to be cleaned as often as the standard electronic air cleaners. It still has to be maintained and serviced regularly and there are electronic components in it that can go out. If you have bad allergies and need the extremely small particles to be filtered out of the air then this is a good system for you.
Another type of filter is the filter that utilizes Ultra Violet (UV) light technology. There are several different designs for these filters with different uses and efficiencies. The main purpose for the UV filter is to eliminate Volatile Organic Compounds (VOC’s). These VOC’s can be chemicals, odors, or organic gasses such as the toxins given off by growing mold and fungi. The so called Self Cleaning filters that only utilize UV lights to filter the air do not work. They may eliminate the Organic compounds, but the inorganic compounds such as polyester fibers and other dust components are not treated. The UV part of this filter is to eliminate Odors and very small particles, and the media part catches the bigger stuff.