Multi Zone Control (MZC III) Zone Board Calibration

The calibration of the Multizone Control (MZC III) zone board is simple and straightforward.

Notes :

• Each probe circuit has a single point calibration potentiometer.
• The procedure is to know the fluid temperature that the probe is in and adjust its pot to reflect that temperature.
• Calibration can be accomplished by turning the chilled water set point up so that all compressors are off.
• Then, place the sensor from a known temperature measurement device into the chiller tank and use this temperature to calibrate the probes following the procedures in steps 2-4 below.
• An ice bath as the known temperature also works well by calibrating to a spare probe, if you have one. The probes are interchangeable to +/- 1.2°F.

How To :

• In the upper left hand corner of the zone board you will find (2) multi turn pots.
• The left one (labeled CALPOT) calibrates the Evaporator In probe (Ei1 on the MZC III instrument display).
• The right one (labeled CALPOT 1) calibrates the Evaporator Out probe (Eo1 on the MZC III instrument display).
• To calibrate the Zone 1 probes, from the MZC III display, press the Zone button until the 'Zone 1" LED light is flashing.
• Then press Select until 'Ei1' is displayed. Use a small, non conductive screw driver to adjust the calibration screw on the multi turn pot until the display's temperature matches your known calibration temperature.
• Make adjustments slowly! The temperature value is averaged over time and there is a small communication lag due to the scanning process within the MZC III instrument.
• Once the Ei1 probe is calibrate, press Select until 'Eo1' is displayed and repeat the procedure.
• Repeat these steps until all probes in all zones are calibrated.

Typical placement of Zone Control boards in central water chillers.