Appendices 59
WARNING
●
Do not adjust or attempt to measure gas valve outlet
pressure. The gas valve is factory-set for the correct
outlet pressure. This setting is suitable for natural gas and
propane, requiring no field adjustment.
●
Attempting to alter or measure the gas valve outlet
pressure could result in damage to the valve, causing
potential severe personal injury or substantial property
damage. Navien NCB500 boilers are shipped ready to fire
natural gas only.
Inner Packing
Outer Packing
Gas Gasket
Gas Orifice
Figure 5. Exploded View of Gas Pipe Assembly
(NCB500)
DANGER
See Figure 5. Inspect the Outer packing between the venturi
and gas valve inlet adapter whenever they are disassembled.
The Outer packing must be in good condition and must be
installed. Failure to comply will cause a gas leak, resulting in
severe personal injury.
Replace the old Orifice piece with the new part for use with LP
gas. Ensure that the Orifice is properly seated inside the port
before proceeding to the next step.
11. Replace the gas inlet pipe to its original position and use all
screws to secure all connections.
Note
Do not overtighten as this may damage or crack
the components.
12. Check the labels carefully and then connect all the wires.
13. Set the front panel DIP Switch to change the gas type.
WARNING
Ensure that you have turned off the power to the boiler
before accessing the DIP switches.
1 2
O
N
Figure 6. Set the DIP switches
Switch Function
Setting
1 & 2
Fuel
Selection
G20 (LNG)
1-OFF, 2-OFF
G30 (LPG)
1-ON, 2-OFF
G31 (LPG)
1-ON, 2-ON
Table 1. The DIP Switch Setting by Fuel Selection
