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COMMISSIONING
GAS PRESSURE WITHIN THE SYSTEM
Refer to the figures below for natural gas or L.P.G gas pressures.
The pressure at the appliance must not be less than the pressure read at
the meter minus:
• 1mbar for Natural Gas
• 2.5mbar for LPG
The pressure drop from the meter to the gas valve must not be more
than:
• 2.5mbar for Natural Gas
• 4mbar for LPG
If the pressure drops are greater than shown below, then this would
indicate a problem with the pipe work or connections within the system.
Meter
Natural Gas
< 2.5mbar
difference
19 - 23 mbar
Boiler inlet
1 mbar
drop
18 - 22 mbar
Fig. 43 Natural gas pressures
≤
Equal to or less than .....
Regulator
L.P.G.
< 4.0mbar
difference
32 - 45 mbar
Boiler inlet
2.5 mbar
drop
29.5 - 42.5 mbar
Fig. 44 LPG pressures
NOTICE:
Do not continue commissioning until the correct gas
pressure is achieved.
40
6.5.2
▶ The gas rate should be measured at the gas meter after 10 minutes
▶ Where a gas meter is not available (e.g. LPG) the CO/CO
▶ If pressure and gas rate are satisfactory press the service button and
▶ Close the gas isolation valve.
▶ Remove the manometer.
▶ Re-seal the screw in the gas inlet pressure test point.
▶ Open the gas isolation valve.
Gas Control
valve
▶ Ensure that there are no gas leaks.
▶ Replace the outer case.
6.6
The following combustion and flue integrity checks are mandatory from
April 2014 and these values must be recorded on the Benchmark check
list, at the back of this manual.
16.5 - 20.5 mbar
Once the gas rate and pressure have been confirmed as acceptable then
the CO and combustion checks can be undertaken.
1.5 mbar
The flow chart is given for guidance, the details of the checks are given in
drop
the following sections:
• Checking flue integrity, refer to section 7.3, page 45
• Flue gas analysis, refer to section 7.5, page 46
6720644744-44.2Wo
Gas Control
valve
28 - 41 mbar
1.5 mbar
drop
6720644744-45.2Wo
Checking the gas rate
operation at maximum.
See technical data section at the front of this manual.
checked to the units shown in the setting of the air/gas ratio, refer to
section 7.6.
the appliance will return to normal operation.
– If left in the service mode the control will return to normal operation
after 15 minutes.
CO AND COMBUSTION CHECKS
NOTICE: BEFORE CO AND COMBUSTION CHECKS:
▶ Refer to section 6.5.1 and 6.5.2 to verify gas type,
gas inlet pressure, and gas rate.
Visually check the integrity of the whole flue system
and confirm that all the components are correctly
assembled, fixed and supported.
▶ The flue gas analyser must be the correct type as
specified in BS 7967. Before use the analyser must
have been calibrated as specified by the
manufacturer.
The installer must be competent in the use of the
analyser.
Check and zero the analyser in fresh air as specified
by the manufacturer.
▶ The gas valve is factory set and must not be adjusted
during commissioning if found to be out of tolerance,
please contact the Worcester, Bosch Group help line
0330 123 3366.
must be
2
6 720 821 670 (2018/06)
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