User Manual Thermal X - R Series Chillers
Page 13
OPERATIONAL LOGIC OF CONTROLLER
Start Up
Pump ON, Ball Valve OPEN (if fitted), 10 second delay and then flow readings are taken to check
pump is running normally. After compressor hold time and water temperature is above the set point
plus hysteresis, COMP1 ON. Once the water temperature reaches set point then compressor OFF.
Unit then waits for both the hysteresis and compressor hold time again and then re-starts compressor.
When there are two compressors such as model R3000 and R4000, the 2
nd
compressor will start after
the set delay start time if required. The logic works as the system will start the 2
nd
compressor at the
higher temperature than the 1
st
compressor after the delay time (hold time). This designed to give the
lead compressor to handle the base load and subsequent compressor acts as a cooling capacity top up.
Temperature Control-Set Point
Controller will turn compressors off when the set point is reached. Compressors will be turned on
again once water temperature reaches set point temperature plus hysteresis.
Temperature Control-Max and Min Set Point
This prevents casual operator from setting supply temperatures too high or too low
Temperature Control-High and Low Temperature Alarm Stop
High and low temperature limits can be set in order that if they are breached then the chiller will shut
down. In rare instances a component may fail without triggering any internal fault indicators. The
chiller may think it is running normally yet not refrigerating. It is recommended that high and low
temperature stop is set to yes to prevent this happening.
Fan Speed Control-Optional
The controller monitors the discharge pressure of each of the refrigeration circuits and makes
decisions for fan speed based on this value. There are 3 ways to control the fans and the settings can
be changed in the controller.
ON ZERO FULL: The fans can be set to shut down while the compressor is running If the pressure
drops below the minimum set point – say on a cold day – then the fans will shut down to prevent over
condensing even though the compressor may still be running.
ON LOW FULL (Default option): In the menu these is a valve for minimum run (default 1500 kPa)
which when reached will start the fans and run them at 20% speed. There is a fan full speed setting
(default 2200 kPa) that will run the fans at full speed. The fan speed will then run proportionally
between these two values. These operational pressures will be different for units supplied with R134a
– see the setting section of the manual
