Exhaust air (alternatively Defrosting) temperature is constantly measured.

The defrosting controller (PID) will take over control of sequence output (exchanger bypass) if temperature falls below [-3] oC.

The flow of cold Outdoor - Supply air is gradually diverted from the exchanger to bypass while the flow of warm Extract - Exhaust air remains unchanged.

The intended imbalance of the air flows through the exchanger reduces transfer of thermal energy and as a result has a defrosting effect.

Configuration of defrosting with temperature monitoring


Available options & Selection


Sequence selection

Configuration > Functions > Function activation > Heating/Cooling sequence setup

Sequence for exchanger

...| SEQ-B Exchanger |...

Select sequence for exchanger

Sequence settings

Configuration > Functions > Function activation > Heating/Cooling sequence setup > Exchanger

Type of sequence

...| Exchanger |...

Type of exchanger

| Rotary | Plate | Liquid |

Type of defrosting

...| Temperature monitoring |...

Defrosting configuration

Configuration > Functions > Temperature control > Defrosting temperature monitoring

Temperature sensor

| Exhaust air | Defrosting |

Extract air fan speed when fan stop defrosting

|Auto | Low | Normal | High |

Operation level of the extract air fan when the supply air fan is stopped

Allocate analog input

Configuration > I/O allocation settings > Analog inputs

Exhaust air temperature

Any available I/O

PID Settings

Configuration > PID controllers > Defrosting


[16] oC

PID settings for the defrosting controller


[240] s


[0] s

Defrost operational settings

Data & Settings > Temperature control > Exchanger > Defrosting temperature monitoring

Setpoint min limit

[-3] oC

Defrosting starts when the exhaust (defrosting) temperature is < -3 oC and will continue until it becomes +1 oC (-3 oC + 4 oC), but not less than 15 minutes

Hysteresis to end defrosting

[4] oC

Min time

[15] min

Stop supply air fan if outdoor temp <

[-100] oC