My son in B.C. recently bought a 4 year old well built raised bungalow with a completely finished basement. The total area of the house is approximately 2400 sq. feet. What he has now noticed is that when it is cold out many of the windows get fogged up due to the humidity in the house. A while ago, on CFRA, I remember you describing how to build a device controlled by a humidstat that would exhaust the moist air to the outside. Could you please identify how to build this device and identify where it would best be located.
Answer:
Actually, it is not controlled by a humidstat but by a timer and the best place to find it is in your workshop because its a DIY project that will take you less than an afternoon to build. And it works! Cold air holds more moisture than warm air and is, therefore, heavier. As air cools, it falls and keeps falling until it reaches the lowest level in the house. It cannot fall beyond the basement floor and that is where it has to be collected and pumped outside before that moisture gets a chance to condense in order to get rid of the moldy, musty odour and/or avoid it in the first place. A booster fan (250 CFM +) is available as a ‘pop in’ unit to fit 4”, 5” or 6” round heating duct. This can be installed in a totally separate duct line that is at least six feet from the nearest heat source. A timer on it will ensure that it operates only during the night (9pm to 9am) so cold, moist air it pumps out is not replaced by air that brings in even more humidity from outside. All joints and seams in the duct are taped and sealed for maximum efficiency and rather than a heating-type grill it should be a return air-type grill. To avoid having to core another hole in the foundation wall, this system can be vented, via a “TY” through the clothes dryer vent. Because none of the doors in the house go all the way to the floor, cold, moist air should find its way to that grill.
