Humidex
12
Unit Operations
How a Humidex Works
Humidex is a mechanical ventilation appliance installed in the
lowest
level of a home, (basement or
crawlspace), engineered to expel moisture-laden air that stagnates due to poor air circulation. Cool,
moist air will gravitate to the lowest point of the home, which is the basement or crawlspace in a
multi-level home and where it can condense on the cooler floor/wall surfaces. The lack of proper
ventilation in the crawlspace creates an environment where the damp air will stagnate and emit
odors, nurture the development of molds, mildew and saturate into the structure, i.e. walls, floors,
frame works, drywall, as well as contents.
A quiet powerful fan in the unit draws the moist surface air in through the bottom vents and then
expels it
out of the house through a 6-inch duct.
The expelled air is replaced with a flow of fresh,
dry, warmer replenishment air drawn downward from the upper level, which raises the temperature
and lowers the relative humidity. The humidistat control in the unit measures the relative humidity
of the air flowing out. When the humidity drops to below the set level, the unit will decrease the
flow of air to a minimum.
The air flow will draw in the s
urface moisture and effectively “dry out” the structure. This decreases
mildew and mold activity by not allowing the moist air to stagnate and nurture their growth.
In the summer, with air conditioning running the replenishment air is dehumidified which will assist
in lowering the relative humidity and in the drying out process.
When there is no air conditioning, the air upstairs is warmer and will raise the dew point downstairs
as it eventually warms the crawlspace to reduce condensation.
In the winter, the air upstairs flows downstairs, this is then replaced by dryer outside air, thus
reducing window condensation and lowering the humidity upstairs. The warmer replenishment air
will raise the downstairs temperature. The heat in the house accompanied with the dry air (Dryer air
requires less energy to heat) will result in the Humidex working at a low speed; enough to maintain a
minimal airflow with minimal energy costs.
The air that flows downstairs is replaced with air that seeps into the house through openings or
building air leakage. The direct effect of the air being expelled and the flow of the air downstairs
create an air exchange in the house several times a day, expelling gases, toxins and contaminants
trapped in the air and providing fresh clean air necessary for good indoor air quality.
In this manner, Humidex helps control the relative humidity level in the home, reduces moisture
related problems and provides recommended air exchanges for a healthy, drier home environment.
Vacant Homes
Performance results are maximized when the building is occupied. If home is vacant for a prolonged
period of time, then the unit should be set to operate at low speed. A fresh air intake supply is
recommended via a small opening in a window upstairs or a supply vent such as the ASV-90.
