30 NCB Service Manual
Version 1.0
c.
Fully open several hot water fixtures and set the boiler
to operate at 1-stage MIN mode (refer to “setting the
DIP Switches” on page 19 and Operation Condition
Setting on page 54).
Measure the CO
2
value at low fire.
If the CO
2
value is not within 0.5% of the value listed in
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 5/32” or 4mm Allen wrench,
turn the set screw no more than 1/4 turn clockwise to
raise or counterclockwise to lower the CO
2
value.
Figure 8. Set Screw Location
NOTE
The set screw is located behind the screw-on cover. This
must be removed first.
d.
Fully open several hot water fixtures and set the boiler
to operate at 2-stage MAX mode (refer to page 19 and
page 54). Measure the CO
2
value at high fire.
If the CO
2
values do not match Table 2 at high fire, do
not adjust the gas valve. Check for the proper Gas
Orifice in Table 3.
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.
Figure 9. Checking offset Gas Pressure with Manometer
b.
Connect a manometer to the offset pressure port. For
dual port manometers, use the positive pressure side.
Model
Kit Part No.
Gas Type
Offset
NCB-180
NAC-01
LP
-0.03"±0.01"
NAC-100
NG
-0.04"±0.01"
NCB-210
NAC-02
LP
-0.02"±0.01"
NAC-200
NG
-0.04"±0.01"
NCB-240
NAC-03
LP
-0.02"±0.01"
NAC-300
NG
-0.04"±0.01"
Table 3. Offset values for low fire
Digital pressure
manometer
Содержание NCB-180
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