Technical information

UGH021/0301 VL Series Portable Chillers, 2 to 40 Tons

Page: 25

B. INSTRUMENT OPERATION

1. When the CHILLER ON rocker switch is toggled on, the

instrument will begin temperature control operations and

the ‘to process’ temperature will begin to drop.

2. When the ‘to process’ temperature drops 1° below the

setpoint, the instrument will activate the capacity control

system to match the cooling capacity to the present load,

as indicated by the HOT GAS BYPASS light (figure 3.3A).

3. If the load is less than the minimum capacity of the chiller,

the ‘to process’ temperature will continue to drop. At 3°

below setpoint the compressor will stop and enter a three

minute time delay period before restarting at 1° above

setpoint. The time delay is to prevent short cycling damage

to the compressor.

C. INSTRUMENT CONTROLS

1. CHILLER ON SWITCH: this rocker switch

engages/disengages electrical supply to the compressor and

pump circuit.

2. SELECT: depress to index through the TO PROCESS and

SET POINT temperatures.

3. UP ARROW: depress and hold this push button to increase

the setpoint temperature. If this push button is pressed

momentarily the setpoint value is incremented by one

degree. If the push button is held down for more than one

second, the setpoint will increase slowly at first and then

faster after about two seconds.

4. DOWN ARROW: depress and hold this push button to

decrease the setpoint temperature. If this push button is

pressed momentarily the setpoint value is incremented by

one degree. If the push button is held down for more than

one second, the setpoint will increase slowly at first and

then faster after about two seconds.

D. INSTRUMENT STATUS DISPLAY

1. POWER: illuminates when the proper supply of electrical

power is applied to the unit.

2. PUMP: illuminates when the CHILLER ON rocker switch is

turned on and the pump is operating. Even with the

CHILLER ON rocker switch on, the PUMP light will not

illuminate if a safety fault condition exists.

3. COMPRESSOR: illuminates when the instrument engages