Nu-Air Ventilation Systems Inc. - HRV Operating &Installation Manual
Revised April 27, 2012
Page 7 of 17
Other Basic Needs (by others)
Galvanized Duct
Flexible Duct Connector
Outside Hoods (2)
Duct Fittings
Duct Tape & sealer
Screws
Diffusers
Duct Hanger
Balancing dampers
Isolation and installation fasteners
6.3
Ducting from the Weather Hoods
Between the weather hoods and the H/ERV it is recommended to use rigid rectangular ducting
equal to or larger than the collar size of the machine. These ducts should be wrapped with an
insulating duct wrap. The minimum RSI value of insulation should equal that of the local
building codes.
6.4
Weather hoods
Designers should try to locate the hoods in such a way that there is easy access for cleaning
purposes. If the H/ERV can be located close to the outside wall(s) containing the hoods, the
resulting short duct lines will minimize airflow restrictions.
6.4.1
Locating the Weather Hoods
There should be maximum separation between the fresh air and exhaust hoods. Supply hoods
should be a minimum of 36” (inches) above the ground level. Exhaust hoods should be at least
24" (inches) above the ground level. Fresh air hoods must be min. 10’ away from any other
appliance exhaust vent or furnace vent.
In addition ASHRAE Standard 62-99 recommends the following. Ventilation systems should be
designed to prevent re-introduction of exhaust contaminants, condensation or freeze-ups and
growth of microorganisms. Make-up air inlets and exhaust air outlets shall be located to avoid
contamination of the makeup air. Contaminants from sources such as cooling towers, sanitary
vents, vehicular exhaust, and street traffic should be avoided.
