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How to Buy a Whole House Air Cleaner

Have allergies? Sensitive to mold, dust mites or other indoor contaminants? A whole- house air cleaner is a device that can be mounted between your furnace and return air duct to trap the airborne particles that might exacerbate these problems. These cleaners are designed to work in addition to your furnace's standard filters, adding an extra level of cleanliness to your home. Numerous options exist to remove the contaminants most bothersome to you and your family from the air you breathe.

Cleaning Options

Whole-house air cleaners run every time your heating and cooling system operates. These devices are installed as part of your central heating and cooling system, generally in your return duct. That means every time your furnace blower moves cold air into your furnace, the air first passes through the air cleaner.

Several types of air cleaners exist. Passive air cleaners are much like your furnace's filter, only these air cleaning devices generally include several layers of dense filters that trap dust, pollen and other particles. The fewer holes the filters have, the more contaminants can be captured. And, much like with your furnace's filters, numerous filter types can be used with these air cleaning systems, including HEPA filters able to remove 99.97 percent of particles 0.3 microns or larger.

However, keep in mind that as they gather dirt these filters can impede the flow of air, making your furnace work harder to circulate air through your ducts. In addition, installing a highly-efficient filter in an older furnace can strain the furnace's blower as it tries to circulate the same amount of air through layers of filters. If this reduced airflow is left unaddressed, your furnace could potentially overheat, have a burner shutdown or suffer a limit switch failure. To prevent such problems, it's critical that you purchase the appropriately filter and regularly clean or replace it. Talk to the air cleaner dealer or your HVAC technician about which air cleaner might work best for you and how often maintenance needs to be performed to keep your furnace running in top condition.

In addition to these passive filter-based systems, there are a number of air cleaners that are able to remove even smaller particles, such as bacteria and viruses, through various electronic technologies. Ionizing cleaners create charged molecules (ions) that attract particles within the air. As these particles are gathered, they become heavy and, ultimately, settle out of the air. Other systems use UV lights; the ultraviolet radiation makes certain micro-organisms sterile and harmless. Still other air cleaners generate ozone, which alters oxygen molecules. While these products' manufacturers say ozone generators deodorize and disinfect the air, the Environmental Protection Agency (EPA) points out that ozone is a known lung irritant and can combine with certain indoor chemicals, such as those from household cleaning products, air fresheners or even carpet, and the resulting "ultrafine particles" may be linked with health problems.

Of course, standalone options exist as well. These cleaners generally are used to clean the air of a single room. These portable air cleaners usually have a fan that circulates the air and use any one of the electronic technologies mentioned above. According to information from the Environmental Protection Agency, for typical room sizes, most portable air cleaners available today are not effective at removing large particles such as pollen, dust mite and cockroach allergens.

Effectiveness

While the Environmental Protection Agency (EPA) notes that there is no measure for the effectiveness of electronic air cleaners, filters generally feature a Minimum Efficiency Rating Value (MERV) from 1 to 20. This value was established by the American Society of Heating, Refrigeration and Air Conditioner Engineers (ASHRAE) to describe a filter's efficiency at trapping contaminants.

Manufacturers generally note on their packaging the percentage of particles that can be removed by their filter, up to as high as 99.9 percent, and the size of particles they can remove, measured in microns, a scientific measurement equivalent to one millionth of a meter.

Experts point out that creating a tight seal between your cleaning system and the duct is important in getting the maximum efficiency from the unit, since it ensures air is flowing through the cleaner, not around it.

Energy and Installation Costs

Upfront costs vary greatly among air cleaners, as do operating costs. A standalone, single-room air cleaner may be as inexpensive as $100, while whole-house versions may run upward of $3,000. Standard passive cleaners may require no additional power source, while ozone or ion generating units will require a power supply, adding to your utility bill. Talk to your furnace maintenance technician about how your air cleaner of choice may impact the efficiency of your furnace and the bottom line on your utility bills.

Although some systems, with a bit of research, can be installed by the homeowner, it might pay in the long run to have a professional contractor take on the task, especially if it involves a modification to your ductwork. Many of these products may require some change to your ducts or need to be wired into your electrical system. For example, UV lamps may require access holes in your ducts, while high-efficiency or HEPA filters may require certain modifications to your sheet metal modifications to allow room for the thicker air cleaner. In some cases, your furnace may require a more powerful fan to overcome the higher pressure drop that occurs when your filter media impedes the flow of air. Because of these system-dependent variables, installation costs will vary greatly.

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