Defrost - Heat Pump - Lennox CLIMATIC 50 User Manual

DEFROST – Heat Pump
Function
Avoid the ice on the Evaporator while the reversible unit works in winter operation
Description
To avoid the icing of the external air exchanger in winter operation, it is necessary to reverse the refrigerant
cycle on a regular basis to de-ice by heating the exchanger.
The defrost is activated when the air temperature is under a set point (3432) and the LP is lower than a set point
(3433)
While defrost is demanded, the defrost cycle is as following:
1. Stop compressor and fans
2. wait 5s
3. reverse 4 way valve
4. wait 5s
5. start compressor
6. When HP reach 22b or compressor are running for more than 4 minutes, stop compressor
7. wait 5s
8. reverse 4way valve
9. start fans at full speed in order to dry the exchanger for a period that can be adjusted with
set point 3435.
10. end of defrost
Two different type of Defrost demand are possible:
•
Dynamic defrost (set point 3431 = Dynamic)
•
Cycling defrost (set point 3431 = Cyclic)
CLIMATIC 50 user manual – Chillers ranges CL50-CHILLERS/IOM/1105-E
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