Compressors - Lennox CL50-RoofTop Installation Operating & Maintenance Manual

COMPRESSORS

Function
From a room temperature need (Capacity Factor) the compressors are started and stopped with a determined sequence
in order to minimize the anti short cycle protection effect and to equalize the operating time.
Description
Compressors Start/Stop sequences.
This sequence is set by the memorized compressor operating time and it also includes the other compressors back-up
function, if they are not available. For circuits with tandem compressors, it is possible to favour the unit performance,
COP, rather than the compressor operating time balance (3642).
The compressor starts if all the following conditions are satisfied:
•
The unit, the compressor and the circuit do not have major faults.
•
The control requires the starting of the compressor.
•
The compressor has the lowest operating time among the stand by compressors.
•
The compressor has not been brought into service for at least 6 minutes.
Every compressor state can be checked on the following menus: 2512, 2522, 2532..., 2562
To check the operating time of each compressor use menus: 2519, 2529....2569
To reset an operating time counter, put the DS50 cursor on the line and press the key `Enter' during 20 seconds.
Compressor operation authorization.
The user may choose to limit the operation of the compressors by using contacts or set points modification.
Outdoor temperature
Cooling mode
Stop of all compressors if the outdoor temperature is lower than the threshold (3612)
Stop of 50% of the compressors if the outdoor temperature is lower than the threshold (3611)
Note: if the option `Low Ambient Kit' is activated (3822) these two functionalities are disabled.
Heating mode (Heat pump)
Stop of all compressors if the outdoor temperature is higher than the threshold (3613)
Set points
Stop of one or several compressors if the compressor number is not displayed in the address (3641)
Cooling mode
Stop of all compressors if the instruction (3355) is set to [No]
Limitation to 50% of the compressors if the instruction (3359) is set to [Yes]
Immediate stop of 50% of the compressors if the instruction (3643) is set to [Yes]
Heating mode (Heat pump)
Stop of all the compressors if the instruction (3356) is set to [No]
Note: Address 3355 and 3356 can be set differently for zones A, B, C, Uno or BMS
Note: The address 3359 can be set differently for zones Uno or BMS
Free contacts (Optional - See Customized Input / Output (BE.50))
Stop of one or several compressors if the compressor number is not displayed in the address (3641)
Stop of 50% of the compressors if the contact
Stop of all the compressors if the contact
High pressure offloading (FLEXY 2 tandem only)
With tandem compressors, it is possible to reduce the circuit capacity by stopping one of the two compressors before the
high pressure reaches its limits in order to keep a partial capacity with high outdoor temperature.
If the condensing pressure is higher than 40b and continuously increases with all the fans in operation at full speed, 1
compressor of the considered circuit is stopped.
CLIMATIC™50 – IOM – Rooftops/ Aircoolair
[Dis. 50%Cp] is close.
[Dis. Cp/Ah] or [Dis. Comp] is close.
CL50-ROOFTOPS-IOM-1107-E
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