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14
Fresh Air Supply System
The fresh air supply ductwork from the HRV may be
directly connected to the return air duct of the forced
air system. Check the air flow balance of the HRV with
the air handler blower both “ON” and “OFF” to
determine that it does not imbalance the HRV more
than 10%. Also, it is advisable to include a short length
of flex duct or other non-metallic connector in this hard
ducted line in order to keep the HRV acoustically iso-
lated and separately grounded (electrically) from the
air handler. This will avoid a possible shock hazard to
service people if a short to ground develops in one of
the devices.
It may be necessary to install a separate fresh air supply
ductwork system if the heating is other than forced air.
When installing an HRV, the designer and installer
should be aware of local codes that may require
smoke detectors and/or firestats in the HVAC or HRV
ductwork.
Because an HRV is designed to bring fresh air into the
building, structures may require supply voltage
interrupt when smoke or flame sensors are triggered,
or when a central fore alarm system is activated.
Supply air grilles may be ceiling or high wall mounted.
Avoid locating incoming fresh air grilles that could
cause a direct draft on the occupants as the incoming
air may be below room temperature. A reheat duct
heater can be installed to improve occupant comfort.
The use of balancing dampers or adjustable grilles to
balance the flow rates into various rooms is
recommended.
The use of balancing dampers or adjustable grilles
as supply air diffusers and air exhaust covers are
recommended. TECHGRILLES™ are round, efficient,
sound absorbing devices available in 4”, 5”, 6” and 8”
(100, 125, 150, and 200 mm) models.
AIR FLOW
SUPPLY
AIR FLOW
EXHAUST
TECHGRILLE
(optional) schematic