Navien NCB500-2S/37K Service Manual page 24

c. Fully open several hot water fixtures and set the boiler
to operate, and proceed Gas Setup Wizard.
For proceeding Gas Setup Wizard for gas type
Note
selection, refer to "4.4.4 Start-Up Wizard" on
page 26.
Measure the CO value at low fire.
2
If the CO value is not within 0.5% of the value listed in
2
Table 2, the gas valve set screw will need to be adjusted.
If adjustment is necessary, locate the set screw as shown
in Figure 8. Using a T15 Hexalobular wrench, turn the
set screw no more than
counterclockwise to lower the CO
Figure 8. Set Screw Location
The set screw is located behind the screw-on
Note
cover. This must be removed first.
Model
Load
Max.
NCB500-2S/37K
NCB500-2S+/41K
Min.
/ turn clockwise to raise or
1
4
value.
2
Gas type
Output
Kcal/h
22,360
3,870
d. After Gas Setup Wizard is done, operate at minimum
mode.
Note
e. Fully open several hot water fixtures and set the boiler
to operate at DHW maximum mode (refer to "4.4.8.5
Setting the Special Operation Modes" on page 37).
Measure the CO
If the CO
2
do not adjust the gas valve. Check for the proper Gas
Orifice.
DANGER
Improper gas valve settings can cause severe personal injury
or substantial property damage.
Consumption
kW kW
26.0 26.8
4.5 4.6
For operation mode selection, refer to "4.4.8.5
Setting the Special Operation Modes" on
page 37.
value at high fire.
2
values do not match Table 2 at high fire,
G20
[20 mbar]
Gas flow
m /h
3
2.870
1.944
G31
[37 mbar]
Gas flow
m /h
3
0.273
0.185
System Details 23