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d. Activate multiple zones and set the boiler
to operate at 2-stage D. MAX mode (refer
to "11.13.7 Setting the Special Operation
Modes" on page 118). Measure the CO
value at high fire.
If the CO
values do not match Table 2 at
2
high fire, do not adjust the gas valve. Check
for the proper Gas Orifice.
WARNING
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. 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.
NAC-
NHB-
NH055-080
055/080H
NAC-L055/080 LP -0.02 in ±0.01 in
NAC-NH110
NHB-
110H
NAC-L110
NAC-NH150
NHB-
150H
NAC-L150
Table 3. Offset value for low fire
126 Appendixes
2
Digital pressure
manometer
Gas
Offset
Type
NG -0.04 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
c. Activate multiple zones and set the boiler
to operate at 1-stage MIN mode (refer to
"11.13.7 Setting the Special Operation
Modes" on page 118). Measure the offset
value at low fire and compare it to the
values in Table 3. If the offset value is out of
range, the gas valve set screw will need to
be adjusted.
If adjustment is necessary, locate the set
screw as shown in Figure 10. Using a
or 4 mm Allen wrench, turn the set screw
no more than
/
turn clockwise to raise or
1
4
counterclockwise to lower the offset value.
Figure 10. Set Screw Location
The set screw is located behind
Note
the screw-on cover. This must be
removed first.
d. At high fire, do not check the offset value
and never adjust the gas valve.
WARNING
Improper gas valve settings can cause severe
personal injury, death or substantial property
damage.
/
in
5
32
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