INSBFNHL1013
BEFORE YOU BEGIN
Ductwork may have a direct impact on fan performance. Therefore, we are proposing the following recommendations.
Ducts
We highly recommend the use of rigid ducts. Flexible ducts increase air restriction, resulting in poor fan performance and increased
noise levels (sones). If flexible ducts must be used, they should be stretched as much as possible to avoid sagging.
GOOD PERFORMANCE – PVC and galvanized steel ducts: these types of ducts greatly reduce static pressure* resulting in optimum airflow. The
fan will not have to work as hard to ventilate, using less energy as a result. The noise levels will be at their lowest.
MEDIUM PERFORMANCE – Flexible aluminum ducts: an affordable option that ensures good fan performance. However, the ridges on these
types of ducts restrict airflow, compromising performance levels.
POOR PERFORMANCE – Vinyl ducts: these types of ducts are low price, but have a lot of ridges. Moreover, their flexible construction restrict
airflow, resulting in higher noise levels.
* Static pressure: airflow resistance that must be overcome by the fan to induce air movement
.
Elbows
An ideal installation would have no elbow at all, but since most realistic applications
require 1, 2 or even 3 elbows, we recommend the following instructions.
The first elbow must be installed at least 70 cm (27 1⁄2’’) from the fan and have a wide
angle to facilitate airflow.
An elbow which is installed too close to the fan or has a sharp angle (90 degrees
or less) could cause a backflow of air into the fan.
Required space
Fan installation requires a vertical clearance of at least 7 inches within ceiling. If the joists have a height
of less than 7 inches, add filler in order to reach that height. Fan housing can be centered between two
joists spaced up to 24 inches on center.
TWO INSTALLATION METHODS
A)
INSTALLATION USING WOODEN HEADERS
(NOT INCLUDED)
• Method used only on unfinished ceilings (see also alternate method B)
• Requires the installation of headers between ceiling joists.
p. 3
B)
INSTALLATION USING SLIDING BRACKETS
• Method used only on unfinished ceilings (see also alternate method A)
p. 6
Note: Some steps are easier to complete with the help of a co-worker. The fan can also be wall-mounted. However, this installation could impede
the proper operation of the back draft damper and, therefore, the unit performance.
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