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The Proportional plus Integral plus Derivative (PID) loop is used to control the output of the LiquidCool, 
reheat, and dehumidify modes. 

Choose which mode or actuator PID loop to tune, using the 01of03: [Mode/Actuator name] setting.

Choose the multipliers to use in the PID algorithm. You can omit the derivative or the integral 

and derivative multipliers in the algorithm.

Note: Controllers that use temperature as the process variable calculate the process error in 
units of Centigrade.

The proportional multiplier (gain) for this mode or actuator. The proportional multiplier adjusts for the 

difference (error) between the measurement (temperature or humidity) and the setpoint. The proportional 
multiplier is expressed in percent of output per unit of error. 

The integral multiplier (reset rate) for this mode or actuator. The integral multiplier adjusts for error 

measurement and the amount of time that the error has existed. The integral multiplier adds to or 
subtracts from the output in small increments to correct for the offset error caused by the proportional 
contribution. It is expressed in percent of output for each minute and unit of error (error multiplied by 
minutes).

The derivative multiplier (derivative) for this mode or actuator. The derivative multiplier adjusts the 

output for rapid changes in the error, correcting for the rate of change of the error over time. It is 
expressed in percent of output for each unit of error per minute (error divided by minutes).

A qualified service technician must tune the PID loops to optimize the performance of each mode. The 
units shown are for temperature. In the dehumidify loop, the units are in percent relative humidity 
(%RH).

Caution: The PID loops must be tuned after the equipment in the room is installed and 
running. The loops should be tuned periodically to account for changes in the room load. 

1. Select the PID loop to tune.

2. Adjust the integral and derivative constants to zero and the proportional constant to twenty. 

3. Set the temperature (cool or reheat) setpoint value and start the System.

4. When the temperature reaches a stable value, increase the proportional constant by 10. If the 

temperature does not respond to this change, adjust the setpoint.

5. Repeat step 4 until the temperature value starts to oscillate and the peak amplitude of the 

oscillations is constant. 

01of03:LiquidCool
Mode: Prop+Int+Der
P: 020 %/°
I: 000 %/°*min

na0

43

2a

D: 000  %/°/min

na

043

3a