Setting The Air/Gas Ratio; Replacement Parts - Bosch Worcester 2000 Series Installation And Maintenance Instructions Manual

Replacement parts

9.9

Setting the air/gas ratio

NOTICE:
Setting the air/gas ratio
▶ The air/gas ratio is factory set and should not need to be adjusted. If
found to be out of tolerance and when all other possible causes have
been checked, please contact the Worcester Bosch Group helpline
0330 123 3366.
NOTICE:
Combustion testing
▶ The checking of the air/gas ratio must be carried out by a competent
registered gas engineer, such as a Gas Safe registered engineer or
British Gas engineer.
▶ Checking of the air/gas ratio must not be attempted unless the
person carrying out the test is equipped with a flue gas analyser
conforming to BS7927 and is competent in its use.
All CO/CO readings must be taken with the combustion chamber cover
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ON.
Adjustments can only be made with the cover off.
CO should be measured 10 minutes after firing the appliance.
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Adjusting the minimum rated output settings
With the appliance in minimum rated output.
▶ Remove the seal from the adjusting screw of the gas valve (only gas
valve is shown in the below Figure 77) and set the CO
for minimum rated output.
4mm
T40
Fig. 77 Setting the CO or O content (above: SIT valve, below:
2 2
Honeywell valve)
58
▶ Re-check settings at maximum and minimum rated output and re-
adjust if required.
▶ Seal the gas valve minimum adjustment.
▶ Exit the chimney sweep mode.
▶ Enter the CO
10 Replacement parts
WARNING:
Mains supplies - Isolate the appliance
▶ Turn off the gas supply and isolate the mains electrical supply before
starting any work and observe all relevant safety precautions.
▶ Drain the appliance/system where necessary and protect any
electrical equipment from water ingress during component
replacement.
WARNING:
Component replacement:
▶ After replacement of a gas carrying component, where a gasket or
seal has been disturbed or replaced, check for gas tightness using a
gas sniffer/leak detection fluid.
▶ On re-assembly check all affected seals for cracks, hardness and
deterioration.
 If damaged or in any doubt the seal must be replaced.
▶ Also after re-assembly, carry out the following checks:
 Fan pressure.
 Flue gas analysis.
Only use Worcester, Bosch Group original spare parts with this
or O content
2 2
appliance. Non Worcester, Bosch Group original spare parts will
invalidate the guarantee (if applicable) and any warranty.
▶ A comprehensive list of appliance spares can be found on the website
www.worcester-bosch.co.uk/spares
contents in the servicing record.
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Worcester 2000 – 6 721 814 551 (2019/09)