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60 Appendices
Model
Gas type
G20
G31
[20 mbar]
[37 mbar]
w
o
l
f
s
a
G
w
o
l
f
s
a
G
n
o
i
t
p
m
u
s
n
o
C
t
u
p
t
u
O
Load
Kcal/h
kW
kW
m
3
/h
m
3
/h
NCB-24LDWE
Max.
16,770
19.5
20.0
2.142
0.804
Min.
3,354
3.9
4.2
0.450
0.169
NCB-28LDWE
Max.
20,124
23.4
24.0
2.570
0.964
Min.
3,354
3.9
4.2
0.450
0.169
NCB-34LDWE
Max.
24,317
28.3
29.0
3.106
1.165
Min.
4,214
4.9
5.1
0.546
0.205
NCB-40LDWE
Max.
28,509
33.2
34.0
3.641
1.366
Min.
3,268
3.8
4.0
0.428
0.161
c. Fully open several hot water fixtures and set the boiler
to operate at 1-stage MIN mode.
Note
For operation
m
ode selection, refer to “10.4
Setting the
O
peration
M
ode” on page 42.
M
easure the C
O
2
value at low fire.
I
f the C
O
2
value is not within 0.5% of the value listed in
Table 2, the gas valve set screw will need to be adjusted.
I
f adjust
m
ent 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
m
ore than
1
/
4
turn clockwise to raise or
counterclockwise to lower the C
O
2
value.
Figure 8. Set Screw Location
Note
The set screw is located behind the screw-on
cover. This
m
ust be re
m
oved first.
d. Fully open several hot water fixtures and set the boiler
to operate at 2-stage D.
M
AX
m
ode (refer to “10.4 Setting
the
O
peration
M
ode” on page 42).
M
easure the C
O
2
value at high fire.
I
f the C
O
2
values do not
m
atch Table 2 at high fire,
do not adjust the gas valve. Check for the proper Gas
O
rifice.
DANGER
Im
proper gas valve settings can cause severe personal injury
or substantial property da
m
age.
Summary of Contents for NCB-24LDWE
Page 65: ...Appendices 65 12 4 Ladder Diagram 3 15A...
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