Lifebreath 1200DD, Installation Manual

Page: 10 / 38

www.lifebreath.com
3
6 S
TALE
A
IR
R
ETURN AND
F
RESH
A
IR
S
UPPLY
S
YSTEM
Stale Air Return System:
Many commercial activities produce air contaminants in the form of dusts, fumes,
mists, vapors and gases. Contaminants should be controlled at the source, so they
are not dispersed through the building or allowed to increase to toxic
concentration levels. The ventilator allows for economical operation of the HVAC
system while effectively removing contaminants from the space. In designing the
exhaust portion of the system, the exhaust grilles are situated to remove the
contaminants while not allowing them to enter the breathing zone of the
occupants.
The stale air return system is used to draw air from the points in the building where the worst air quality problems occur.
Balancing dampers and/or adjustable grilles are recommended on all return air lines which are used during installation to
help balance the “draw” from different areas of the building.
For contaminants lighter than air, grilles should be located high on the wall. If contaminants are heavier than air, a lower
placement of the grilles will be required. Information on a contaminants specific gravity and toxicity should be available
from chemical data sheets.
Alternately, the stale air may be drawn directly from the return air duct. When this system is used, the air handler’s
blower must constantly operate. The exhaust take-off connection must be at least 3 ft (1 m) from a directly connected
ERV supply duct if both are connected to the same duct run. Note and compensate for the static pressure of the air
handlers return system if the static pressure of the return in the air handler exceeds .1 to .15” W.C.
A damper located just prior to the HRV is required to balance the stale air exhausted with the fresh air supply entering
the building.
Return air suction points should be located on the opposite side of the room from the fresh air inlet. The inlets may be in
the ceiling or high on the walls and fitted with inlet grilles.
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 isolated 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.
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 fire alarm system is
activated.
It may be necessary to install a separate fresh air supply ductwork system if the heating is other than forced air.
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.