3. Confirm the selection.
The boiler is now set to low load.
Checking/setting values for O
2
at low load
1. Measure the percentage of O
2
in the flue gases.
2. Compare the measured value with the checking values in the table.
Tab.38 Checking and setting values for O
2
at low load for G20 (H
gas)
Values at low load for G20 (H gas)
O
2
(%)
(1)
C 330 ECO
4.8
(1)
- 5.4
C 630 ECO
4.8
(1)
- 5.4
(1) Nominal value
Caution
The O
2
values at low load must be higher than the O
2
values at
full load.
3. If the measured value is outside of the values given in the table,
correct the gas/air ratio.
4. Using the adjusting screw B, set the percentage of O
2
for the gas type
being used to the nominal value. This should always be inside the
highest and lowest setting limit. The direction in which the adjusting
screw must be turned to increase or decrease the gas flow is
indicated on the gas valve unit.
Important
The 5- to 9-section boilers are supplied with a different gas valve
unit from the 10-section boiler. See drawing for the position of
adjusting screw B for full load.
5. Check the flame through the inspection window.
Important
The flame must not blow off.
6. Repeat the full load test and the low load test as often as necessary
until the correct values are obtained.
7. Set the boiler back to the normal operating status.
Fig.60
bar
1
1
2
2
r
c
STD
(
'
t
v
0 2 4 6 8 10 12 14 16 18 22 2420
p
b
AUTO
x
c
g
m
r
j
M
GENE :
BOILER TEMP.
CURRENT
WIND SPEED
PMIN
68°C
10µA
1850 tr/min
a
C002348-F-04
AUTO => PMIN
Fig.61 Adjusting screw B
7 Commissioning
7600532 - v.11 - 13122018 53
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