14.0Servicing the Boiler
14.1Annual Servicing
WARNING: The PCB Control and Fan Assembly are 325 Vdc. Isolate system controls before access.
IMPORTANT: When servicing ensure that both the gas and electrical supplies, including Switched and Permanent Live to the boiler are isolated before any work is started.
The four LEDs on the facia will all be OFF.
It is important to isolate the electrical supply at the system isolation switch as it is not possible to do this on the boiler itself.
Hazardous materials are not used in the construction of this product, however reasonable care during service is recommended - see Section 1.2.
When replacing the combustion box door after servicing it is essential that the retaining screws are tightened fully.
1.For reasons of safety and economy, it is recommended that the boiler is serviced annually. Servicing must be performed by a competent person in accordance with B.S.
2.After servicing, complete the relevant Service Interval Record section of the Benchmark Commissioning Checklist at the rear of this publication.
IMPORTANT: During routine servicing, and after any maintenance or change of part of the combustion circuit, the following must be checked:-
•The integrity of the complete flue system and the flue seals.
•The integrity of the boiler combustion circuit and relevant seals as described in Section 14.2.
•The operational gas inlet pressure as described in Section 12.2.1 to 12.2.3 and the gas rate as described in 12.2.4.
•The combustion performance as described in ‘Check the Combustion Performance’ (14.1.4 to 14.1.6 below).
3.Competence to carry out Checking Combustion Performance
B.S. 6798 ‘Specification for Installation & Maintenance of Gas Fired Boilers not exceeding 70kW’ advises that:-
•The person carrying out a combustion measurement should have been assessed as competent in the use of a flue gas analyser and the interpretation of the results.
•The flue gas analyser used should be one meeting the requirements of BS7927 or
•Competence can be demonstrated by satisfactory completion of the CPA1 ACS assessment, which covers the use of electronic portable combustion gas analysers in accordance with BS 7967, Parts 1 to 4.
Check the Combustion Performance (CO/CO2 ratio)
4.Set the boiler to operate at maximum rate as described in Section 12.2.
5.Remove the cap from the flue sampling point, insert the analyser probe and obtain the CO/CO2 ratio. This must be less than 0.004.
6.If the combustion reading (CO/CO2 ratio) is greater than this, and the integrity of the complete flue system and combustion circuit seals has been verified, and the inlet gas pressure and gas rate are satisfactory either:
• Perform the ‘Annual Servicing - Inspection’ (Section 14.2) &
• Replace the gas valve (Section 15.8) &
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