6 720 611 449 GB (03.11)
34
Converting the appliance to different gas types
8
Converting the appliance to different gas types
The setting is factory sealed at maximum. Adjustment to
the rated heat input and min. heat input is not neces-
sary.
Checking the gas supply pressure
B
Check the gas supply pressure at the gas supply
pressure testing point.
Natural gas
• Appliances for
natural gas type G20
are factory set
to Wobbe-Index 15 kWh/m
3
and 20 mbar supply
pressure and sealed.
8.1
Setting the gas/air ratio
The gas/air ratio may only be adjusted on the
basis of a CO
2
measurement at max. heat output
and min. heat output using an electronic tester.
B
Switch off the appliance at the master switch (
O
).
B
Remove the outer case (see page 15, refer to
fig. 13).
B
Switch on the appliance at the master switch (
I
).
B
Unscrew sealing plug from flue gas testing
point (234). Refer to fig. 41.
B
Insert testing probe about 135 mm into the flue gas
testing point and seal testing point.
Fig. 41
B
On the text display unit, select in the main menu
Set-
tings, Service, Display service parameters
.
B
Press and hold the
button (for about 5 sec-
onds) until the display shows
Adjust service
parameters
and the first service function to be set,
2.0 Operating mode
. If a fault has occurred, the
display will show 0.0 and the last fault.
B
Press
or
until the display shows
2.0
Operating mode normal
.
B
Press the
button.
B
Press
or
to select Max.
B
Measure the CO
2
level.
B
Prise off the seal on the gas flow restrictor.
B
Adjust the gas flow restrictor (63) to obtain the CO
2
level given in Table 14. Refer to fig. 42.
Fig. 42
B
Press
or
to select Min.
B
Measure the CO
2
level.
B
Remove the seal from the gas valve adjusting screw
(64) and adjust the CO
2
level to the figure given in
Table 14 for min. rated heat output. Refer to fig. 43.
Fig. 43
B
Recheck the levels at min. and max. rated heat output
and re-adjust if necessary.
i
Natural gas appliances must not be oper-
ated if the gas supply pressure is below
18 mbar or above 24 mbar.
LPG appliances must not be operated if
the supply pressure is below or above
37 mbar.
6 720 610 599 - 01.TD
234
ZSBR 7-28
Gas Type
CO
2
reading
at max.
rated heat
output
CO
2
reading
at min.
rated heat
output
Natural gas type
G20
9.2 %
8.8 %
LPG G31
(propane)
10.8 %
10.5 %
Table 14
63
6 720 610 332-64.1R
64
3928-74.1R
