16
17
6. Interior Ducting
Ducting to the central forced air ductwork system, or if used, a dedicated duct
system, should be made of galvanized metal whenever possible.
To minimize airflow losses, runs should be kept as short as possible using 45
degree elbows instead of 90 degree. Whenever possible use “Y” fittings instead
of “T” fittings.
All joints must be fastened with screws, rivets or duct sealant and wrapped
with a quality duct tape to prevent leakage. If standard grills are used, it is
recommended that wall grills of not less than 6” x 12” and floor grills of no less
than 4” x 10” be used to minimize air flow restrictions.
7. Fresh Air Supply Ducting
Fresh air supply ducting to the living space may be either a dedicated or an
indirect duct system. Please refer to figures I and II.
Should the indirect method be used it is suggested that at the point of
connection to the HRV that a short length of flex duct be used to electrically
isolate the two systems.
Fresh air supply grills may be either wall or ceiling mounted. Avoid locating
these grills where room occupants may be exposed to the fresh air supply as this
air temperature may be slightly less than the room air temperature.
Also, it is recommended that adjustable grills such as round “Tech Grills” be
used to permit balancing of the ventilation by room application.
It is recommended that a breathing “T” be installed in the fresh air duct between
the HRV and the central distribution system. This will maximize efficiency, but
hard connection is acceptable.
