Navien NFC-250/175H, Руководство по установке, Страница: 134 / 151

134 Appendixes
c. Activate multiple zones and set the boiler to
operate at 1-stage MIN mode.
Note
For operation mode selection,
refer to “11.6.7 Setting the
Special Operation Modes” on
page 126.
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
in
or 4 mm 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. Activate multiple zones and set the boiler
to operate at 2-stage D. MAX mode (refer
to “11.6.7 Setting the Special Operation
Modes” on page 126). 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.
DANGER
Improper gas valve settings can cause severe
personal injury, death or substantial property
damage.
The DIP SW1 (Set of 6 Switches) on the circuit board
configures the operation status and model settings.
1 2 3 4 5 6
O
N
O
N
1 2 3 4 5 6 7 8
Switch Function Setting
1 & 2
Operation
Status
Normal
Operation
1-OFF, 2-OFF
2-stage MAX 1-ON, 2-OFF
1-stage MIN 1-OFF, 2-ON
1-stage MAX 1-ON, 2-ON
3 & 4 Reserved - -
5 & 6 Model
NFC-
250/200H
5-OFF, 6-OFF
NFC-
250/175H
5-ON, 6-OFF
Model Altitude Fuel
High fire Low fire
%CO
2
%CO
2
NFC-
250/175H
NFC-
250/200H
0-5,399 ft
Natural
Gas
8.8 8.9
Propane
Gas
10.5 10.7
5,400-
10,100 ft
Natural
Gas
8.8 8.9
Propane
Gas
10.5 10.7
Table 2. CO
2
value
(CO
2
values must be within 0.5% of the
values listed.)