HP POD 20c Maintenance And Service Manual page 46

You need a wrench to remove and replace the pressure sensors.
Removing the chilled water supply and return header pressure sensor
Observe the sensor alignment direction.
1.
Disconnect the sensor wiring.
2.
Using a wrench, disconnect the sensor from the tubing connection by rotating the nut counterclockwise.
3.
Remove the sensor from the water piping.
4.
Replacing the chilled water supply and return header pressure sensor
Position the sensor as it was prior to removal.
1.
Connect the sensor to the sensing tube.
2.
Using a wrench, rotate the sensor retaining nut clockwise to tighten it.
3.
Reconnect the sensor wiring.
4.
Removal and replacement procedures 46