ECONOMIZER
HRV/ERV FRESH
AIR SUPPLY
HRV/ERV UNIT
STALE AIR
EXHAUST TO ERV
SUPPLY DUCT
RETURN AIR DUCT
or BREATHER T
FRESH AIR
SUPPLY
STALE AIR
EXHAUST
ROOFTOP
UNIT
B.D.
B.D.
ROOFTOP
UNIT
HRV/ERV FRESH
AIR SUPPLY
SUPPLY DUCTWORK
CEILING RETURN AIR PLENUM
ROOF DECK
STALE AIR EXHAUST
HRV/ERV UNIT
ECONOMIZER
12" BREATHER
SPACE
B.D.
B.D.
FRESH AIR
SUPPLY
STALE AIR
EXHAUST
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
removes 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 obsolete in conjunction with an
HRV.
Many buildings have ceiling return air plenum as in
Figure B. Fresh air from the HRV can be introduced
directly into the ceiling space but this should occur
near the air handler’s intake.
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 effectively 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 .
The
Integrated
HVAC
System
When
interlocking
a
rooftop
unit
with
an
HRV/ERV,
care
must
be
taken
to
ensure
the
fans
of
both units operate in the correct
rotation.
CAUTION
These
Illustrations
are
examples.
Be
sure
to
verify
the
duct
configuration
of
intake exhaust on and the unit you are
installing.
ATTENTION
21
