20
ROUTINE SERVICING
6
T
o ensure continued efficient operation of the appliance, it is
recommended that it is checked and serviced as necessary at
regular intervals. The frequency of servicing will depend upon the
particular installation conditions and usage, but in general once a
year should be adequate. It is the law that a competent person,
such as British Gas or other CORGI registered personnel, must
carry out any service work.
Before commencing any service operation, ISOLATE the mains
electrical supply, and TURN OFF the gas supply at the main service
cock.
Service the appliance by following the full procedure detailed below:
6.1
COMBUSTION CHECK
The appliance incorporates a flue sampling point on the appliance
flue elbow, or appliance vertical flue adaptor. If suitable
equipment to analyse the flue gas is available, remove the
sampling cap and fit a 6 mm inside diameter sample tube.
When the appliance is operating at maximum output check that
the gas supply pressure is 20mbar, using the inlet pressure test
point located on the main gas service cock.
Check also the flame current of the detection electrode (see
Fig.23).
Remove casing panels and ease control panel down for access.
Connect a multimeter across connectors of the detection electrode
as shown. The measured value shall be approximately 0.7
µ
A
(Microamps). If the value is less than stated please clean the
electrode with a wire brush.
Operate in DHW mode, at full rate. After ten minutes operation
check the CO
2
/CO values and compare with those figures stated
in section 2.3. Do not forget to replace the sampling cap after use.
If the measured combustion values are significantly outside
the figures stated in section 2.3 check heat exchanger
blockage, flue blockage, burner cleanliness etc.
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