Swegon GLOBAL PX Operation And Maintenance Instructions page 59

8.21 TYPE 20: ALARM INDICATING THAT THE DEFROST PROCESS IS ACTIVE
- Conditions:
• Unit with counter flow heat exchanger.
- Causes:
• The ice forming inside of the plate heat exchanger is genrating a pressure drop that is too high for the current airflow.
This detection requires a Modbus pressure sensor placed on the heat exchanger and that the modulation
of the fans speed is based on the airflow and not on torque.
• When the previous detection is not available, the supply T° is checked and if it falls below 11°C, it is considered
that is due to the ice that reduces the heat exchanger efficiency.
- Effects:
Code
A.20 Defrost
ALARM OUTPUT
/
Operation and maintenance instructions
Displayed on HMI TACtouch
Text displayed
TAC control board
AL dPa OUTPUT
/
Auto reset: yes
LED ALARM
ON
Level
1
Fans
Supply stopped
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