Commissioning
Condens 7000 WP – 6721842519 (2022/03)
22
8.3
Air/gas ratio control valve switch-off options
Air/gas ratio control valve overview
Fig. 29 Test port and adjusting screw overview
[1]
Adjusting screw CO
2
/O
2
(full load)
[2]
Gas inlet pressure test port
[3]
Gas/air ratio test port
[4]
Adjusting screw CO
2
/O
2
(low load)
[5]
Without function
8.4
Measuring the gas standing pressure (static)
The gas standing pressure must be stable to guarantee correct operation
of the boiler. The measurement is carried out when the floor standing
boiler is switched off.
▶ Switch off the appliance.
▶ Remove the front panel.
▶ Open the gas standing pressure test port by turning the adjusting
screw through 2 revolutions (
▶ Set the pressure gauge to “0”.
▶ Connect the pressure gauge to the test port.
▶ Measure the static gas standing pressure.
▶ Make a note of the value in the commissioning report (
§ 16.6,
p. 49).
▶ Close the inlet pressure test port.
8.5
Measuring the gas dynamic working pressure
The gas pre-charge pressure must be stable to guarantee correct
operation of the boiler. The measurement is performed at full load.
As the measurement is taken at the air/gas ratio control valve and not the
gas valve, the permissible gas pre-charge pressure may be reduced due
to the pressure drop between the gas valve and air/gas ratio control
valve.
Example:
GC7000WP 145 to natural gas H, G20.
• Permissible gas pre-pressure: min. 17 mbar – max. 25 mbar (
Tab. 26, p. 48).
• The pressure drop between gas isolation valve and air/gas ratio
control valve is 2.4 mbar (
Tab. 8).
Permissible limit values on the air/gas ratio control valve:
Min. 17 mbar – 2.4 mbar =
14.6 mbar
.
Max. 25 mbar – 2.4 mbar =
22.6 mbar
.
Table 8 Pressure drop between gas valve and air/gas ratio control valve
▶ Calculate the permissible minimum and maximum gas pre-pressure.
▶ Switch off the appliance.
▶ Remove the front panel.
▶ Open the gas pre-charge pressure test port by turning the adjusting
screw through 2 revolutions (
▶ Set the pressure gauge to“0”.
▶ Connect the pressure gauge to the test port.
▶ Make sure the heating system can release its heat.
▶ Operate the appliance.
▶ Open the menu
Function check > Burner
.
▶ Start the
Function check
by setting the value to 100%.
▶ Check whether the measured value lies within the calculated limit
values.
If the measured value lies outside the calculated limit values, do not
commission the boiler. The cause must be established and the fault
rectified. If this is not possible, shut off the gas supply to the system and
contact the gas supplier.
▶ Make a note of the measured value [mBar] after 1 minute in the
commissioning report (
▶ Deactivate
Function check
.
▶ Close the pre-charge pressure test port.
8.6
Measure CO
2
and CO
The CO content in the flue gases must be less than 250 ppm (0.025 %
by volume) during combustion without excess air. If the CO content
exceeds 250 ppm, this will be due to pollution of the burner, malfunction
of the burner or recirculation of the flue gases.
To guarantee the correct setting of the air/gas ratio control valve, first a
CO
2
test is carried out at full load. Then a second measurement is carried
out at low load. Both measurements are carried out in direct succession.
CO
2
test at full load
▶ Switch off the appliance.
0010040861-001
1
3
2
4
5
Max. pressure drop for each gas type
[mbar]
Type
G20
G25 / G25.3
GC7000WP 125
2.2
3.0
GC7000WP 145
2.4
3.3
