|Ask The Expert Question 3, July 2008
What are the pros and cons of portable and furnace-mounted air cleaning products and why would one company want to choose one product to sell over another?
Many versions of both are on the market, though portable units are the most widely available. In most cases, portable units only can treat the air that gets to the machine. Some high-quality portable systems can deliver the appropriate balance of airflow and efficiency; however, they will only be capable of filtering the air that is recycled around to it. Portables can act as a partial or whole-home solution if you are delivering enough air where it is ventilating clean air throughout the ductwork of the rest of the home.
Furnace-mounted systems usually incorporate lower efficiency filters due to pressure drop of the filter; standard heating and cooling systems will not tolerate high-efficiency filters. Standard furnace systems will only treat the air when the fan is running; the only way to effectively treat air is through 24/7 operation. Ultraviolet (UV) systems have become popular, but to be truly effective in the ductwork, measurement of bulb intensity and airflow, velocity by the bulb for proper decontamination of bio-aerosols is crucial. In most cases, this is too expensive to be done residentially. Bypass HEPA systems (recent market arrivals) only treat about 10 percent of the air the furnace is pushing through. Bypassing the main system with 200 cfm of clean air, when the standard heating and ventilation system is meant to treat 2,000 cfm, results in a mere 10 percent being cleaned. Some companies provide installation, though that can add 15-20 percent to the cost of the product, while increasing the companys liability.
Vinny Lobdell, Jr., HealthWay Home Products Inc.
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