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HE-Series Outdoor
ERV
UNIT PLACEMENT
4.3 SOUND ATTENUATION
Take these simple steps to attenuate noise from the unit.
4.3.1 Outside the Building
The exhaust hood is the primary source of noise outside the building. When practical, orient the
exhaust air hood to point away from houses or public areas.
4.3.2 At the Curb
Cut the holes in the roof deck to fit closely around the duct(s) passing through the roof deck.
Seal all gaps around the duct(s) at the roof deck.
4.3.3 Ducts
Make sure the ductwork at the unit outlets is stiff enough to resist the flexure and resulting
booming associated with system start-up and shut-off, as well as the turbulent flow conditions
at the blower outlets.
In general, provide smooth transitions from the ERV’s outlets to the duct. The ducts connecting
to the outlets should be straight for a sufficient distance, with gradual transitions to the final
duct size.
These guidelines are consistent with SMACNA recommended duct layout practices for efficient
and quiet air movement. Follow SMACNA guidelines.
4.3.4 Radiated Noise
The HE1.5XRT is insulated with high-density fiberglass. This provides significant attenuation
of radiated sound from the unit itself.
The outlet ducts can be significant sources of radiated sound as well. The FA duct should be
insulated for sound control. This insulation should start at the unit. At a minimum the first 10' of
duct should be insulated. All parts of the FA and RA ducts located in a mechanical space with
noise-generating equipment also should be insulated for sound control, both to minimize sound
radiation out of the FA duct, and also to control sound radiation into both ducts.
4.3.5 Connecting Horizontal Ducts to Unit
Flanged duct connections are provided on the horizontal duct connections of the HE1.5XRTR,
RTF, and RTH units. These allow for connection of ducts insulated on the inside or the outside,
or for installation of lined duct. Please refer to dimension drawings for duct flange sizes.
