Combination Boiler
Model
NCB-180/210/240
This boiler is configured for Natural Gas
from the factory. If conversion
to Propane Gas is required, the
conversion kit supplied with the boiler
must be used.
WARNING
This conversion kit shall be installed by a qualified service agency* in
accordance with Navien America’s instructions and all applicable codes and
requirements of the authority having jurisdiction. The information in these
instructions must be followed to minimize the risk of fire or explosion or to
prevent property damage, personal injury or death. The qualified service
agency is responsible for the proper installation of this kit. The installation is
not proper and complete until the operation of the converted appliance is
checked as specified in the manufacturer’s instructions supplied with the kit.
٭
A qualified service agency is any individual, firm, corporation or company
which either in person or through a representative is engaged in and is
responsible for the connection, utilization, repair or servicing of gas
utilization equipment or accessories; who is experienced in such work,
familiar with all precautions required, and has complied with all of the
requirements of the authority having jurisdiction.
In Canada
: The conversion shall be carried out in accordance with
the requirements of the provincial authorities having jurisdiction
and in accordance with the requirements of the CAN‐B149.1 and
CAN1‐B149.2 Installation Code.
Tools Required:
Phillips Screwdriver
Flathead Screwdriver
5/32 in or 4mm Allen Wrench
Combustion Analyzer or Dual Port Manometer
Gas Leak Detector
Included Items:
Gas Orifice (refer to below table)
Model
NG
LP
1STAGE
2STAGE
1STAGE
2STAGE
NCB-180
Ø4.80
Ø5.95
Ø3.80
Ø4.70
NCB-210
Ø6.10
Ø6.30
Ø4.50
Ø4.80
NCB-240
Ø6.10
Ø6.30
Ø4.50
Ø4.80
Table 1. Orifice Size
Gas Pressure and Conversion Kit Number Labels
11.
Once the Gas Orifice is exposed, remove the two screws that
hold the part in place. Remove the Gas Orifice from its housing
and prepare the new Gas Orifice for the LP conversion for
installation.
Figure 4. Access to Gas Orifice in Fan Assembly
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, death or substantial property damage. Navien
NCB boilers are shipped ready to fire natural gas ONLY.
Figure 5. Exploded View of Gas Pipe Assembly
DANGER
See Figure 5. Inspect the O-ring between the gas valve and gas valve inlet
adapter whenever they are disassembled. The O-ring must be in good
condition and must be installed. Failure to comply will cause a gas leak,
resulting in severe personal injury or death.
Procedure:
1. Turn off both gas and water supply to the boiler.
2. Using a Phillips screwdriver, remove 4 screws (2 from the top and 2 from
the bottom) of the front cover assembly to gain access to the internal
components. See Figure 1 for illustration of the front cover on the unit.
3. Once the front cover is removed, place it in a safe location to prevent
accidental damage.
4. Label all the wires on the PCB.
5. Disconnect all the wires.
6. Loosen the three screws indicated in the figure. (Refer to Figure 2.)
7. Remove the PCB assembly.
8. With the internal components exposed, locate the gas inlet
pipe and the gas valve in the middle of the unit.
9. Use a Phillips screwdriver to remove the two screws at location
A - the connection below the gas valve where it connects to the
pipe. See Figure 3 for reference. Once the screws are removed,
carefully separate the pipe from the gas valve.
10.
Once the gas inlet pipe is detached from the gas valve, find
location B - the connection above the gas valve where it is
attached to the fan motor assembly. Carefully remove the four
screws by hand using a Phillips screwdriver and pull the gas
valve away from the fan assembly to access the gas orifice.
Figure 3. Detaching Gas Valve from
Gas Inlet Pipe and Fan Motor Assembly
Figure 6. Orifice identification
12.
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.
13.
Replace the gas inlet pipe to its original position and use all
screws to secure all connections.
Do not overtighten as this may damage or crack the
components.
DANGER
Inspect the O-ring between the gas valve and gas valve inlet adapter
whenever they are disassembled. The O-ring must be in good condition
and must be installed. Failure to comply will cause a gas leak, resulting
in severe personal injury or death.
14.
Place the PCB assembly back on to the boiler and tighten the
three screws.
15.
Check the labels carefully and then connect all the wires.
16.
Set the front panel Dip Switch to change the gas type. For LP, set Dip
Switch 2 #2 to On. For NG, set DIP SW2 #2 to Off.
WARNING
Ensure that you have turned off the power to the boiler before accessing the
DIP switches.
DANGER
When conversion is required, be sure to set the front panel DIP
switches according to the supply gas type.
Failure to properly set the DIP switches could cause carbon
monoxide poisoning, resulting in severe personal injury or death.
17.
Turn on the gas and water supply to the boiler.
Location B: Remove
4 screws here
Location A: Remove
2 screws here
Figure 1.
Figure 2.
Gas Orifice
O-ring
Remove two (2)
screws here
