Navien NCB-150E Service Manual page 31

Model Fuel
NG
NCB-150E
LP
NG
NCB-180E
LP
NG
NCB-210E
LP
NG
NCB-240E
LP
Table 2. CO
(CO values must be within 0.5% of the values listed.)
2
c. Fully open several hot water fixtures and set the boiler to
operate at 1-stage MIN mode.
For operation mode selection, refer to "4.4.11
Note
(3) Operation conditions Settings" on page
56.
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 /
5
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.
30 NCB-E Service Manual
High fire Low fire
%CO %CO
2 2
8.9 9.5
10.2 10.8
8.9 9.5
10.2 10.8
8.9 9.5
10.2 10.8
8.9 9.5
10.2 10.8
value
2
in or 4 mm Allen wrench, turn
32
/ turn clockwise to raise or
1
4
value.
2
d. Fully open several hot water fixtures and set the boiler to
operate at 2-stage D. MAX mode. Measure the CO
high fire.
If the CO values do not match Table 2 at high fire, do not
2
adjust the gas valve. Check for the proper Gas Orifice.
DANGER
Improper gas valve settings can cause severe personal injury,
death or substantial property damage.
Option 2. Using Digital Manometer
a. Open the offset pressure port by loosening the screw two
turns as shown in Figure 9.
Digital pressure manometer
Figure 9. Connect Digital Pressure Monometer
b. Connect a manometer to the offset pressure port. For dual
port manometers, use the positive pressure side.
Model Kit Part No. Gas Type
NAC-N5
NCB-150E
NAC-L5
NAC-400
NCB-180E
NAC-04
NAC-500
NCB-210E
NAC-05
NAC-600
NCB-240E
NAC-06
Table 3. Offset value for low fire
value at
2
Offset
NG -0.04 in ±0.01 in
LP -0.03 in ±0.01 in
NG -0.04 in ±0.01 in
LP -0.03 in ±0.01 in
NG -0.04 in ±0.01 in
LP -0.02 in ±0.01 in
NG -0.04 in ±0.01 in
LP -0.02 in ±0.01 in
Version 1.4