Main Logic; Cooling Mode; Heating Mode - Gree HLR35SM/NaA-M Service Manual

MODULAR MINI CHILLER

2 MAIN LOGIC

2.1 Cooling Mode

2.1.1 Control of Compressor
1 Start-stop Control--- "first start, first stop; first stop, first start"
During running of the unit, the compressor is numbered instantly. It is controlled according
to the principle of "first start, first stop; first stop, first start".
2 Water Temperature Drop (Rise) Rate Control
The water temperature interval is the main control, while the temperature drop (rise) rate is
the auxiliary control. This can adapt to the load variation of the terminal, keeping water
temperature stable and avoiding fierce variation. In this control mode, the system is based on
the temperature and temperature drop rate: when the water temperature is too high and if the
temperature drop is rapid, it means the output load is bigger than the terminal load. In that
case, it is not necessary to startup the other compressor. The temperature interval and
temperature drop is decided by experience, other theories and test so that the water
temperature can be kept stable and frequent stop can be avoided.
2.1.2 Anti-freezing Protection
For each module, when the anti-freezing temperature is lower than the required value for
protection, the anti-freezing protection will start then the compressor of this module will stop.
When the anti-freezing temperature is higher than the required value for resume, this system
will eliminate the anti-freezing protection.
When the anti-freezing temperature is between the above two temperature, it will not affect
the anti-freezing protection.
If the unit is low temperature unit, the anti-freezing protection is invalid.
2.1.3 Stop of the Unit
Stop the unit manually or via timer: the compressor stops and then the fan stops. After
certain control time, the water pump will stop.
Stop the unit upon reaching a temperature spots: the compressor stops and then the fan
stops (on condition that both compressor stops). The water pump will not stop.
Disorderly closedown: the compressor stops and then the fan stops (except the
malfunction of the fan). After the corresponding compressor stops for a period. The water
pump will not stop.

2.2 Heating Mode

2.2.1 Control of Compressor
The control principle is the same with that of cooling mode.
2.2.2 Superheat Protection
For each module, when the superheat temperature is higher than the required value for
protection, the superheat protection will start then the compressor of this module will stop.
When the superheat temperature is lower than the required value for resume, this system will
eliminate the superheat protection.
When the superheat temperature is between the above two temperature, it will not affect
the superheat protection.
2.2.3 Control of Auxiliary E-heater
CONTROL
10