PGC, Inc 500-1000 CFM Air Handler May 2006
Appendix A A-22
WATER TEMPERATURE CALIBRATION
The water RTD (RTD1) can be calibrated via the user interface. This sensor was calibrated prior
to shipment and typically will not require re-calibration. However, if calibration is necessary refer
to the SmartPad™ user interface manual for details regarding the water RTD calibration screens.
The water RTD can be calibrated by plugging precision resistors in place of the RTD, or by
comparing the temperature measured by the water RTD with a reference standard. In either
method, the RTD can be calibrated using a zero and span adjustment, or it can be calibrated to a
single offset point. If the single offset point adjustment is required, use the Zero routine.
Water RTD Calibration Procedure with Reference Standard:
1.) Zero Offset, or Single Point Offset.
a. Place the reference standard (NIST traceable thermometer or thermocouple) in
the center of the sump, half-way down in the water.
b. Operate the system at the minimum water temperature; or if performing a single
point offset calibration, operate the system at the desired offset temperature.
c. Access the RTD calibration screens in the SmartPad™:
• On the Process Variables screen, press MORE (F4), then PREF (F2), and
enter the access code (factory setting: 0000) to access the Area
modification screen.
• Press CAL (F3) to access the Water Calibration screen.
d. Enter the temperature measured by the reference standard and press ZERO (F1).
e. Press “CAL” (F1); after a few seconds, observe the Actual Value matches the
Reference Value.
f. Press “DONE”.
2.) Span (Gain) Adjustment:
a. Operate the system at or near the maximum water temperature and allow several
hours for the temperature to stabilize.
b. Access the RTD calibration screens in the SmartPad™:
• On the Process Variables screen, press MORE (F4), then PREF (F2), and
enter the access code(factory setting: 0000) to access the Area modification
screen.
• Press CAL (F3) to access the Water Calibration screen.
c. Enter the temperature measured by the reference standard and press SPAN (F2).
d. Press “CAL” (F1); after a few seconds, observe the Actual Value matches the
Reference Value.
e. Press “DONE”.
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