Re: Furnace Odor Aerobic bacteria - mold- mildew
Posted by More on April 27, 2002 at 15:51:29:
In response to Re: Furnace Odor Aerobic bacteria - mold- mildew
The furnace uses a rectangular sheet metal plenum to collect the air that is blown past open flame, and an air filter by a squirrel cage fan and allow changes of direction for the heat and a/c ducting. The plenum is dark (no ultraviolet light such as sunlight to kill bacteria ), warm, and enjoys slight moisture from the heated air wringing the water vapor from the cooler cold air return. This is a wonderful breeding ground for bacteria and mold, and mildew spores. They grow on the walls of the ducting and on the bottom of the plenum, because the forced air heat is hotter and lighter than air, and doesn't scrub the bottom of the duct with air friction. When you change to cooler air conditioning, it is heavier than air and therefore flows with air friction against those mold and mildew spores, and scrubs them from their breeding colony, and from the duct floor and scatters them into the wind. Odor comes directly to the highest elevation because the warm air rises and the lighter than air aerobic bacteria, mold and mildew spores are riding on those air currents through the ductwork, to the highest elevation bedrooms.

Look in your area for professional duct cleaning contractors, and make sure they are LICENSED and BONDED. You are referring to indoor air pollution which is concentrated and pushed upon you and your children in even higher concentrations than commercial buildings because of the tightness of your home, the shading of windows from direct sunlight ultraviolet light waves, and vapor barrier construction. Ultraviolet light waves vibrate at a frequency that 90 percent reduces the ability of mold and mildew to reproduce, which renders them non toxic. Your continual year after year exposure could lead to allergies, respiratory afflictions, and breathing difficulties which are greatly heightened in young children and elderly folks, and presons whose immune systems are in disorder.

A LICENSED duct cleaner will create a negative air space prior to beginning the duct work which will drag the mold and mildew spores backwards through a HEPA filter (High Efficiency Particulate Air) and capture the very high concentrations in the breeding colony BEFORE beginning brush and vacuum cleaning of the plenum and duct work. Ask a LICENSED duct cleaner about the ability to install an Ultraviolet Light box with automatic circuitry inside your plenum when the work is done. E-mail me if you need more information at

: For the past couple of years we have noticed a very foul odor coming from our upstairs furnace vents. It occurs when the season changes and we go from running heat to running the AC. I've heard that it could be mold in the furnace and that it can be cleaned. Any ideas?

: Thanks

: Ron

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