HE3XINV Due to continuing product development, specifications are subject to change without notice. © 2012 RenewAire LLC
134772_006 HE3XINVMan_Jan12.indd Revised 01/2012 www.renewaire.com
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Inside Ductwork System
Follow Engineer’s Ductwork Design
Ductwork should be designed by an engineer to allow the unit to
provide the required airflow.
Design Tips
Air Flow Rates
Design the system to provide the lowest air exchange rate that will
accomplish the ventilation goals. At lower air flow rates, energy
recovery effectiveness improves. See Product Data Sheet.
Duct Transitions
Ducts should enter and exit the unit through smooth, gradual
transitions.
Duct Insulation:
If the inside ducts run through un-conditioned spaces, they must
be insulated, with a sealed vapor barrier on both inside and
outside of insulation.
Picking up Stale Air in the Building
Locate the stale air pick-ups high in rooms where moisture, odor,
or other contaminants are generated.
If some duct runs are much shorter than the others, install dampers so
you can balance flows. Most rooms require only one stale air pick-up.
Duct Fresh Air from the HE3XIN into the heated space
Fresh Air from the HE3XINV often can be ducted into an existing HVAC
air distribution system.
Sometimes, however, it is more practical to install a separate
distribution system for the Fresh Air.
The Fresh Air supplied by the HE3XINV will be somewhat cooler or
warmer than room air in very cold or hot weather. Consider this when
deciding how to distribute the Fresh Air.
Connection of Fresh Air from HE3XINV to ducted heating & cooling
system:
Avoid a situation in which operation of the main air-handling blower
unbalances flow through the HE3XINV. (See Balance the Air Flows,
below). This is a particular concern if the HE3XINV is to be operated
on a different schedule from the main air-handler. Minimize the effect
of the air-handler on the HE3XINV by connecting Fresh Air from unit at
a point well upstream from the air handler.
Balance the Air Flows
The air flow rate for both the Fresh Air and the Exhaust Air should be
roughly equal (or “balanced”) for best performance of the HE3XINV. If
the HE3XINV is connected to an existing air-handling system it may be
necessary to check for balance with and without the main air-handling
blower in operation.
In some facilities a slight positive or negative pressure in the building
is desired. RenewAire heat recovery ventilators can generally operate
with a flow imbalance of up to 20% without appreciable loss in heat
recovery efficiency. However, very low exhaust air flow rates may
result in frosting of the core during extremely cold weather.
DO NOT PLACE ANY PICK-UPS IN GARAGES, LOADING
AREAS OR IN FUME HOODS!
Make the Ducts from the Stale Air Pick-ups to the
HE3XINV as simple and direct as possible.
Sound Attenuation
General Practices
Take these simple steps to attenuate noise from the unit.
Outside the building:
Exhaust velocity noise is the primary cause of unit-related noise
outside the building. Size the exhaust duct and grille for less
than 1000 fpm air velocity. When practical, orient the exhaust air
hood to point away from houses or public areas.
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.
Radiated Noise
The HE3XINV is insulated with high-density fiberglass. This
provides significant attenuation of radiated sound.
The outlet ducts can be significant sources of radiated sound
as well. The FA and EA ducts (outlet ducts) should be insulated
for sound control. This insulation should start at the unit. At a
minimum the first ten feet of duct should be insulated. All parts
of the FA and EA ducts located in the mechanical space should be
insulated for sound control, both to minimize sound radiation out
of these ducts and also to control sound radiation into the ducts.
Aerodynamic (Velocity) Noise
When sound attenuation is a design concern, the primary
consideration is velocity noise at the unit’s Fresh Air blower
outlet. The average velocity at the blower outlets is 3520 FPM
when the unit is operating at 3520 CFM.
The HE3XINV weighs approximately 640 lbs. It is the
installer’s responsibility to make sure that the screws
or bolts used for securing the units are properly
selected for the loads and substrates involved. Secure
the HE3XINV so that it cannot fall or tip in the event
of accident, structural failure or earthquake.
