Control Water Vapor, Control Mold

  June 4, 2009

Keeping water in check inside of facilities is an important step in preventing mold and mildew problems, which compromise the indoor air quality. Mold can grow with 70 percent humidity. Water can be introduced to the indoor environment in all sorts of ways — from cooking and showering to burst pipes or spills. Water vapor also moves through buildings as part of the air that is mechanically introduced or that infiltrates past the building’s shell.

Some simple operating guidelines for the HVAC system can help reduce the effects of moisture intrusion. In the summer, thermostats should be between 70 and 80 degrees. Letting the temperature be any warmer would reduce the equipment run times and limit its effectiveness in controlling humidity. Any cooler, and moisture condensation on surfaces could become a problem. In the winter, indoor temperatures should not fall below 55 degrees to prevent pipes from bursting.

Also, for unitary or split-system equipment, the fan should be set to the AUTO mode. This allows the fan to cycle on and off with the compressor, which helps avoid introducing unconditioned outside air or the re-introduction of moisture from the cooling coil.    


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