18
Damper Defrost
MODEL RNC5-TPD
The 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 sup-
ply air from ouside allowing the exhaust air to recirculate
through the unit. After the defrost period, the damper oper-
ates in the opposite direction to reopen the fresh air port.
Defrost cycle repeats until the temperature again rises
above 27°F (-3°C).
Fan Defrost
MODEL RNC5-TPF
The fan defrost HRV is equipped with an electronically
controlled fan defrost system to remove frost that collects
on the warm air side of the aluminum heat transfer sur-
faces of the heat exchanger core. When the outside air
temperature drops below 27°F (-3°C), defrost is activated
which provides for an automatic defrost cycle. During the
automatic defrost cycle the fresh air supply is shut off
while the exhaust fan continues to operate. This allows
warm inside air to flow through the heat exchanger core
melting frost accumulation. After the defrost period, the
fresh air supply fan automatically returns to the normal
speed and fresh outside air continues to be drawn into the
building. Water from the melted frost collects in the bottom
drip pans and drains out through the bottom drain connec-
toions. The defrost cycle repeats automatically until the air
temperature rises above 27°F (-3°C).
Defrost Operation
Dehumidistat Operation (HRV only)
Defrost Cycle DIP Switch Settings
The optional HRV remote controls include a dehumidistat
which controls humidity levels during the heating season.
The control has a selector knob with setpoints ranging
from 20% to 80% relative humidity (RH). Most people are
comfortable when indoor relative humidity levels are in a
range from 30 to 45%.
The dehumidistat switches the ventilator to high speed
when the moisture level in the home exceeds the desired
setpoint. The dehumidistat switches the HRV back to low
speed ventilation when humidity has been reduced below
the set point.
The dehumidistat should only be used
during the heating season.
It must be set to the OFF
position throughout the rest of the year.
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.
Lengthening the run time may result in ice
buildup on the core.
CAUTION
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
