Humidex
9
Replenishment air to Basement from Upstairs
The damp air exhausted by the Humidex must be replaced by the warmer/drier air from the upper levels. If
there is no open stairwell, the airflow is restricted from coming down; then install a passive return grille with
100 sq. inches either in the door, in the wall, or in the floor to allow unobstructed air downstairs.
When the flow is limited or inaccessible between rooms downstairs (if there are walls or partitions), then install
a grille 8” x 10” (or other grill configuration, having total area of not less than 80 sq. in.) in the bottom of the
door or wall to avoid having stagnant air in those areas. Otherwise interior doors must remain open. This
insures that all the air drawn into the Humidex comes from all areas of the basement.
In the initial period after installation, before the Humidex has had time to dry out the basement, and when the
air outside is hot and humid; keep the basement/crawlspace doors, windows and vents closed to the outside.
This will assure that the air is replenished with the air from upstairs and not with the humid air from outside.
Generally, for improved performance, it is best to keep all exterior basement/crawlspace doors, windows and
vents closed at all times.
Please check to make sure there are no openings/leaks around windows, doors, vents or other places, where
outside humid air can enter the basement/crawlspace. Make sure that A/C Ducts are properly sealed and that
all A/C Leads to the basement are closed. Sump Pumps holes should be properly covered.
Ducting
The HCS-BS comes in two sections that allow for flexibility in positioning the duct at the most
convenient height. For both models you can duct from the back of the unit, or from the top of the
unit by removing the top cover. The duct can go through an outside wall, the floor joist or window.
The duct should be vented above ground level to the outside or below ground into a window well that
is open and not sealed off to the outdoors. The outside louver should be high enough to avoid
infiltration of snow, flooding and rodents, etc. All necessary parts and outside louvers are included.
In cases where the basement height clearance is too low, the top portion of the bottom section can
be cut down by a maximum of 40 inches with a cutter, leaving the vents at the bottom intact, for a
The replenishment air area must have a minimum size of 100
sq.in.
