3095
10
GB
4.5
COMBUSTION CHECK
It is advisable to set the burner according to the type of gas used and following the indications of the table:
IONIZATION CURRENT
The minimum current necessary for the con-
trol box operation is 5 µA.
The burner normally supplies a higher cur-
rent value, so that no check is needed. Any-
way, if you want to measure the ionization
current, you have to open the connector
(CN1)
(see electrical scheme page 7) fitted on the wire and insert a microammeter.
4.6
AIR PRESSURE SWITCH
Adjust the air pressure switch after having performed all other burner adjustments with the air pressure
switch set to the start of the scale.
With the burner operating at the required power, slowly turn knob clockwise until burner locks out.
Then turn the knob anti-clockwise by about 20% of the set point and subsequently check to see if burner
has started correctly. If the burner locks out again, turn the knob anti-clockwise a little bit more.
The burner leaves the factory with the pressure switch set at the beginning of the scale.
Attention:
As a rule, the air pressure switch must prevent the air pressure from lowering below 80 % of the adjustment
value as well as preventing the CO in the fumes from exceeding 1% (10,000 ppm).
To check this, insert a combustion analyser into the chimney, slowly close the fan suction inlet
(for example
with cardboard)
and check that the burner locks out, before the CO in the fumes exceeds 1 %.
4.7
BURNER START-UP CYCLE
Lock-out is indicated by a lamp on the control box (4, fig. 1, page 2).
EN 676
AIR EXCESS: max. output
λ
≤
1.2
– min. output
λ
≤
1.3
GAS
Theoretical max. CO
2
0 % O
2
Setting
CO
2
%
CO
mg/kWh
NO
x
mg/kWh
λ
= 1.2
λ
= 1.3
G 20
11.7
9.7
9.0
≤
100
≤
170
G 25
11.5
9.5
8.8
≤
100
≤
170
G 30
14.0
11.6
10.7
≤
100
≤
230
G 31
13.7
11.4
10.5
≤
100
≤
230
D4631
+
_
SO
CN1
Fig. 10
Thermostat
Motor
Ignition transformer
Valve
Flame
Lock-out
40s min.
3s max.
40s min.
3s max.
Lock-out, due to light failure
A
Normal
D6236
Servomotor
8
–
27s
8
–
27s
A
