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1.800.627.4499
GR90, EV90, EV90P
ERV
UNIT PLACEMENT
2.4 DUCTWORK APPLICATIONS
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FOR HOUSES WITHOUT DUCTED HEATING OR COOLING SYSTEMS–SEE FIGURE 2.4.1.
In most houses one or two fresh air grilles in a central part of the house provide effective
distribution of the fresh air into the home, particularly when the stale exhaust air is picked
up at several points. Because the fresh air is not fully conditioned, the fresh air supply grilles
should be located in a traffic area like a hallway or stairway rather than in a sitting area. If
you want to get fresh air into specific rooms with high occupancy, you can split up the fresh
air supply.
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FOR HOUSES WITHOUT DUCTED HEATING OR COOLING SYSTEMS–SEE FIGURES 2.4.0, 2.4.2,
AND 2.4.3.
Most units are installed with the fresh air duct connected directly to a return duct for the
main heating and cooling system. Be careful to connect the fresh air duct at least three feet
from the return plenum to minimize suction from the furnace blower. A connection closer to
the furnace may result in unbalanced flow and associated problems.
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FOR INSTALLATIONS THAT COLLECT STALE AIR FROM SPECIFIC ROOMS IN THE HOME–SEE
FIGURES 2.4.0 AND 2.4.1.
Locate stale air return grilles (RA) in rooms where moisture and odors are generated:
bathrooms, the kitchen, and perhaps other areas where contaminants are generated such as
in the home workshop. Return grilles in these other areas may be dampered so that they can
be shut off when not in use. A central location such as a hallway is also acceptable but won’t
clear humidity and odors from baths and kitchens as rapidly. Locate stale air return grilles
(RA) near the ceiling on inside walls. Stale air returns are usually easiest to install in interior
partitions.
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STALE AIR RETURN GRILLE SIZES
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BATHROOM:
4" x 10" or 6" x 10"—40 to 60 sq. in.
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KITCHEN:
6" x 10"—60 sq. in.
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CAN AN ERV BE USED TO VENTILATE BATHROOMS?
A RenewAire ERV can be used as a central exhaust system in place of bathroom exhaust
fans. Tie a grille in each bathroom directly back to the ERV—see Figure 2.4.0. A successful
installation should provide at least 50 CFM of exhaust per moisture producing bathroom.
When used for bathroom exhaust, the EV90/P should be used for only one bathroom. Install a
control in the bathroom ventilated by the ERV.
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FOR HOUSES WHERE RADON IS A CONCERN.
The first line of defense against radon should always be techniques that prevent the entry
of radon into the home, such as under-slab suction, vented perimeter drainage, and crack
sealing. However, if moderate levels of radon continue to be present, it is important that
the unit slightly pressurize the basement, not de-pressurize the basement. Installation of
this unit for radon mitigation is beyond the scope of this manual. Consult a radon mitigation
professional.
See Figures 2.4.0 through 2.4.3 for examples of some common installation approaches.
NOTE: For all units:
RA = Room Air into
unit
OA = Outside Air into unit
SA = Supply Air to inside
EA = Exhaust Air to outside
FA = Fresh Air to inside
