User Guide

10
The Integrated HVAC System
When interlocking a rooftop unit with an HRV,
take care to ensure the fans of both units oper-
ate in the correct rotation.
The HRV has become an integral component of the
HVAC system. Figure A shows an HRV unit providing
fresh air directly to the return air plenum of a rooftop
heat/cool unit.
In the balanced airflow system, the HRV exhaust re-
moves stale room air (eg. from lunch room, storage or
copy area) and returns to the space an equal amount of
fresh outdoor air, making the use of an economizer ob-
solete in conjunction with an HRV.
Many buildings have ceiling return air plenum as in Fig-
ure B. Fresh air from the HRV can be introduced directly
into the ceiling space but this should occur near the air
handler’s intake.
By operating the HRV on a 24 hour / 7 day battery
backed timer, the unit can be set to operate only when
occupancy or indoor conditions require the air exchange.
In installations where it is satisfactory to provide general
exhaust from the space, the air to be exhausted may be
taken directly from the return air plenum to the HRV as it
is drawn back to the air handler. Fresh air supplied by
the HRV is then introduced directly into the return air
plenum but at a location closer to the air handler. The air
handler would have a constant running blower to effec-
tively distribute the fresh air and remove the stale air.
Balancing dampers would be located in both the HRV
supply and exhaust ducts between the return air plenum
and the HRV.
NOTE: At no time should the air handler T.E.S.P.
on the return duct exceed that of the HRV .
Figure A
Figure B
CAUTION
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