Calibrating a Pneumatic T-Stat

1. Determine the throttling range for your control system.  Let’s use 3-13#’s as an example.
2. Next measure the ambient temperature at the thermostat with a precision temp meter.
3. Adjust the setpoint knob on the T Stat to the current ambient temperature.
4. Pull the branch line off the T-Stat and T tap a gauge between the T-stat and branch line.
5. Adjust the calibration screw in the T-Stat until the branch PSI reads zero.
6. Now adjust the calibration screw in the opposite direction until the branch pressure reads mid range. In this case our differential  is 10#’s of pressure, so (13-3)= 10(diff) /2 or 3+5 = 8 psi.
7. Verify the box damper and reheat valve(if applicable) are both closed. Fine tune if needed.
8. Remove your calibration gauge and replace the branch line back onto the T-Stat.
9. Adjust the T-Stat to the desired setpoint.

Your T-Stat is now calibrated…