Dehumidistat Operation (HRV only)
The optional HRV remote controls include a dehumidistat which controls humidity levels during the heating season. The control has a selector knob with set points 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 building exceeds the desired setpoint. The dehumidistat switches the HRV back to low speed ventilation when the humidity has been reduced below the setpoint. The dehumidistat should only be used during the heating season. It must be set to OFF position throughout the rest of the year.
Defrost Operation
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 the warm inside air to flow through the heat exchanger core melting frost accumulation. After the defrost period, the
fresh air supply fan 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 of the drip pans and drains out through the bottom drain connections. The defrost cycle repeats automatically until the air tem- perature rises above 27°F
Defrost Cycle DIP Switch Settings
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.
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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