- Determine the throttling range for your control system. Let’s use 3-13#’s as an example.
- Next measure the ambient temperature at the thermostat with a precision temp meter.
- Adjust the setpoint knob on the T Stat to the current ambient temperature.
- Pull the branch line off the T-Stat and T tap a gauge between the T-stat and branch line.
- Adjust the calibration screw in the T-Stat until the branch PSI reads zero.
- 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.
- Verify the box damper and reheat valve(if applicable) are both closed. Fine tune if needed.
- Remove your calibration gauge and replace the branch line back onto the T-Stat.
- Adjust the T-Stat to the desired setpoint.
Your T-Stat is now calibrated…