Navien CH-180 Service manual - page 115

©Navien America Inc. 2010

CH  series service Manual

113

Version 1.0

6.2. Measuring Gas Pressure Setting

6.2.1. How to Check Inlet Gas Pressure

Procedure to measure the inlet gas pressure: 

THIS SECTION IS ONLY TO BE DONE BY A LICENSED 

PROFESSIONAL

All Safety messages will refer to potential hazards. Precisely follow the 

instructions to avoid the risk of injury.

1. Shut off the manual gas valve on the supply gas line.

2. Open a hot faucet. The unit should turn on and the gas in the gas pipe line    

    should purge. Leave the faucet on to keep the unit running until the unit shuts 

    down due to lack of gas supply. Then shut off the hot faucet.

 3. Remove the screw for the pressure port located on the gas inlet of the boiler.

4. Connect a manometer to the pressure port and reset it to zero.

5. Re-open the manual gas valve. Check to see that there are no gas leaks.

6. Open multiple fixtures that have high flow rates (bathtub, showers, kitchen sink) 

    to ramp the boiler up to its maximum burn.

7. When the Navien boiler is at maximum burn, check the inlet gas pressure read

    ing on the manometer; it should read between 6.0”~10.5” W.C for Natural gas 

    between 8.0”~13.5” W.C for Liquid Propane.

8. The maximum inlet gas pressure must not exceed the value specified by the 

    manufacturer and that the minimum value listed is for the purposes of input 

    adjustment.

Pressure test port on gas line 

The Navien water heater cannot operate properly without sufficient inlet gas pressure 

and volume. Below are instructions on how to check the inlet gas pressure.