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Recirculating Damper Defrost (4 port models)
The recirculating damper defrost HRV has an electronically
controlled damper defrost mechanism. The defrost timer is
activated when the outside temperature drops below 27°F (-
3°C). A motor driven damper door mechanism closes off the
supply air from outside allowing the exhaust air to recirculate
through the unit. After the defrost period, the damper operates in
the opposite direction to reopen the fresh air port. Defrost cycle
repeats until the temperature again rises above 27°F (-3°C).
Damper Defrost (5 port models)
The damper defrost HRV has a fifth port for defrost. An
electronically controlled damper defrost mechanism activates
the defrost timer when the outside temperature drops below
27°F (-3°C). A motor driven damper door mechanism closes off
the supply air from outside allowing room air to enter through
the fifth port of the unit. After the defrost period, the damper
operates in the opposite direction to reopen the fresh air port.
Defrost cycle repeats until the temperature again rises above
27°F (-3°C).
Defrost Operation
Lengthening the run time may result in ice
buildup on the core.
CAUTION
Defrost Cycle DIP Switch Settings - Increasing the Run Time
Defrost DIP Switch Settings (located on the circuit board) can be
adjusted to increase the unit’s run (ventilation) time. The three
minute defrost time cannot change.
HS
REMOTE
DFR2
DFR3
ON
SW1
*Lengthening the run time may result in ice build-up on the core.
HS
REMOTE
DFR2
DFR3
ON
SW1
HS
REMOTE
DFR2
DFR3
ON
SW1
OFF ON
OFF
ON
Factory Setting
3 minute defrost time
17 minute run time
Option 1*
3 minute defrost time
25 minute run time
Option 2*
3 minute defrost time
30 minute run time
FRESH AIR
FROM OUTSIDE
STALE AIR
TO OUTSIDE
FRESH AIR
TO INSIDE
FILTERS
BLOWERS
RECIRCULATING
DEFROST
DAMPER
MOTOR
CORE
STALE AIR
FROM INSIDE
STALE AIR
TO OUTSIDE
FRESH AIR
FROM OUTSIDE
STALE AIR
FROM INSIDE
FRESH AIR
TO INSIDE
BLOWERS
DEFROST
DAMPER
DEFROST
PORT
FILTERS