Qmark ASRV14 - Attic Ventilators User Manual

Page 2

GENERAL INFORMATION

For a power attic ventilator to effectively cool, it should provide at least ten air changes per hour. To
determine the proper CFM rating for a fan that will provide that number of air changes, the total square
footage of an attic must be multiplied by .7. This will give the CFM rating for the fan needed for an attic.
Example: for a home with 1500 square feet of attic space, the calculation would be as follows:
1500 x .7 = 1050. A fan with 1050 CFM rating would be needed for such an attic. For dark roofs, 15%
should be added to this CFM calculation. If a roof is particularly steep, a slightly higher CFM rating
should be sought.

The air intake area must be adequate for proper operation of the power attic ventilator. One square
foot of free open air inlet per 300 CFM of fan capacity is recommended. See “Attic Intake Area
Required” section.

Along with the power attic ventilator’s summer advantages, it also offers home protection during the
winter. In winter months, moist air creeps into the attic from the house below, condensing on the
underside of the roof boards, beams and other materials. Excessive moisture can rapidly deteriorate
these materials. It can also penetrate insulation, reducing its effectiveness and making the home less
energy efficient. An accessory dehumidistat can be used with this power attic ventilator to automati-
cally activate unit in the winter to combat excessive moisture.

The power attic ventilator is designed for ventilating attic space. Do not use unit to exhaust dirt, dust,
grease or lint laden air.

INSTALLATION

NOTE: For maximum operating efficiency, the proper intake air opening must be provided to allow replace-
ment of exhaust air. See “Attic Intake Area Required” section.

The unit should be installed as close to the center of the roof ridgeline as possible on the rear slope
of the roof. The uppermost portion of ventilator dome should be just below ridge level. See Fig. 1.

After locating unit in desired installation position on top of roof, measure from the unit to the ends of
the roof and to the ridgeline. Using these measurements, locate the spot inside the attic directly under
the spot on the roof where the unit has been placed. Locate a centerline position between two rafters
as close as possible to this established position and drill a pilot hole through the roof from the inside.
See Fig. 2.

FIG. 1

FIG. 2

Front

Drill Hole

Rafter