Trane CXAJ series Installation, Operation And Maintenance Manual page 33

Single system
When the system is started, the water pump operates immediately. Two minutes later, the water
pump continues to operate. When the water return temperature is over 15 ℃ , the compressor
will be started. If the cooling requirement is reached, the water return temperature will be
reduced to 10 ℃ , and the compressor will be stopped. Then, the load is increased. If the water
return temperature rises to 15 ℃ , the compressor will be restarted. Unless the unit is shut down,
the water pump will keep running.
Heating mode:
Dual system
When the system is started, the water pump operates immediately. Two minutes later, the water
pump continues to operate. If the water return temperature is lower than 39 ℃ , No.1 compressor
will be started. One minute later, if the water return temperature is lower than 37 ℃ , No.2
compressor will be started. If the heating requirement is reached, the water return temperature
will be increased to 41 ℃ , and No.1 compressor will be stopped. If the water return temperature
is continuously increased to 42 ℃ , No.2 compressor will be stopped. Then, the load is changed,
the water return temperature is reduced to 39 ℃ , and No.2 compressor runs. If the water return
temperature is reduced to 37 ℃ , No.1 compressor will be started. Unless the unit is shut down,
the water pump will keep running.
Single system
The operation of water pump, fan and compressor for the single-unit system is the same as the
above dual-unit system. The only difference is that the compressor will be started if the water
return temperature of the single-unit system is lower than 37 ℃ and will be stopped if the water
return temperature is higher than 42 ℃ .
Table 2.
Unit Operation (H Type)
Temperature sensor (TH2)
The temperature sensor (TH2) senses the water outlet temperature of the system as the basis for
compressor start or stop in the cooling and heating modes.
Cooling mode:
Dual system
When the system is started, the water pump operates immediately. Two minutes later, the water
pump continues to operate. If the water outlet temperature is higher than or equal to 8 ℃ ,
one compressor will be allowed to be started; if the water outlet temperature is higher than or
equal to 9 ℃ , two compressors will be allowed to be started; if the water outlet temperature is
higher than or equal to 10 ℃ , three compressors will be allowed to be started; if the water outlet
temperature is higher than or equal to 11 ℃ , four compressors will be allowed to be started.
Unless the unit is shut down, the water pump will keep running.
Operation Range of Ambient Temperature
Cooling mode 18 ℃ ~ 43 ℃
Heating mode -10 ℃ ~ 21 ℃
Unit Operation
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