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25. Frost protection operation of the heat exchanger
On cross-flow heat exchanger frost can be present during the winter season.
The detection of the risk of frost formation can be done either by a contact coming from a frost protection thermostat or by
a frost protection sensor placed on the heat exchanger.
To activate the detection using a contact, set
015
=14 (DI1) or
017
=14 (DI2) or an analogue input configured as a “frost
protection heat exchanger contact”
019
=21 (AI1) or
021
=21 (AI2) or
023
=21 (AI3).
To activate the detection using a frost protection sensor on the heat exchanger, set
019
=4 (AI1) or
021
=4 (AI2) or
023
=4 (AI3).
I
n case of a frost protection on heat exchanger, it is possible to select, by parameter 186, which action to do for defrosting.
If
186
=0 the speed of the supply fan is reduced relative to the extract fan. The parameter 187 allows you to select the
percentage of the speed reduction.
If
186
=1 the bypass is open, allowing the heat recovery air to heat the heat exchange device plates.
If
186
=2 a pre-heating electrical resistance placed on the heat exchanger is activated. In this case, carry out the following
settings:
If
186
=3 the speed of the supply fan is reduced relative to the extract fan and the bypass is open. The parameter 187 allows
you to select the percentage of the speed reduction. The bypass is open, allowing the heat recovery air to heat the heat ex
-
change device plates
Se
186
=4 the speed of the supply fan is reduced relative to the extract fan and a pre-heating electric heater placed on the heat
exchanger is activated. The parameter 187 allows you to select the percentage of the speed reduction.
If a pre-heating electrical resistance, placed on the heat exchanger, is used, do the following settings:
- select which digital output will control the pre-heating electrical resistance 025=15 (DO1) or 026=15 (DO2) or 027=15 (DO3)
or 028=15 (DO4) or 029=15 (DO5)
- select a sensor with frost protection function for the heat exchanger
019
=4 (AI1) or
021
=4 (AI2) or
023
=4 (AI3).
The pre-heating resistance is controlled based on the following logic:
ON
OFF
Texch.
2°C
185
ON
OFF
Treg
2°C
Anti Frost
189
Res.
Res.: pre-heating electrical resistance
Texch.: frost protection temperature sensor of the heat exchanger
185
: heat exchanger frost protection setpoint
If Texch <
185
i
s activated, the pre-heating resistance is activated and the
icon is displayed, the
and
icons flash
and the message
ALC
is displayed on the alarms page.
If Texch >= (
185
+ 2°C), the pre-heating resistance is disabled, the
, and
icons switch off.
If the frost protection sensor in the heat exchanger has an error, the frost protection operation of the heat exchanger is disabled.
