Defrost Operation
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
Damper Defrost (5 port models)
FRESH AIR
FROM OUTSIDE
RECIRCULATING 
FILTERS DEFROST 
DAMPER
CORE
STALE AIR
TO OUTSIDE
STALE AIR
FROM INSIDE
BLOWERS
MOTOR
FRESH AIR
TO INSIDE
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
FRESH AIR
FROM OUTSIDE
DEFROST |
DAMPER |
DEFROST |
PORT |
FILTERS |
STALE AIR |
FROM INSIDE |
STALE AIR
TO OUTSIDE
BLOWERS
FRESH AIR TO INSIDE
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.
CAUTION
Lengthening the run time may result in ice buildup on the core.
Factory Setting |
| Option 1* |
| Option 2* | ||||
3 minute defrost time | 3 minute defrost time | 3 minute defrost time | ||||||
17 minute run time | 25 minute run time | 30 minute run time | ||||||
|
| ON |
|
| ON |
|
| ON |
|
|
|
| |||||
HS
REMOTE
DFR2
DFR3
HS
REMOTE
DFR2
OFF DFR3
| HS |
| REMOTE |
| DFR2 |
ON | DFR3 |
OFF
ON
SW1 | SW1 | SW1 |
*Lengthening the run time may result in ice build-up on the core.
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