Baxi Potterton BBU 15 HE manual Annual Servicing

Flue Sampling Plug

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. 7967-4.

2.After servicing, complete the relevant Service Interval Record section of the Benchmark Commissioning Checklist at the rear of this publication.

3.Disconnect the firefront electric supply. Remove the fascia from the firefront. Unhook its hanging brackets from the slots in the top of the firefront. On Classica and Innova models also disengage the retaining magnets at the lower part of the fascia.

4.Slacken the firefront retaining wire and unthread it from the bracket on top of the boiler. The firefront can now be manoeuvred away from the boiler. Do not drag the firefront as it may damage the hearth. To completely remove the firefront disconnect the boiler control cable.

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 flue system and the flue seals, as described in Section 7.2.

The integrity of the boiler combustion circuit and relevant seals as described in Section 9.2.

The operational gas inlet pressure as described in Section

8.2.14to 8.2.16 and the gas rate as described in 8.2.17. The combustion performance as described in 9.1.5 to 9.1.6.

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.

Off Position

On Position

Fig. 42

The flue gas analyser used should be one meeting the requirements of BS7927 or BS-EN50379-3 and be calibrated in accordance with the analyser manufacturers’ requirements.

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

5. Set the boiler to operate at maximum rate as described in Section 11.1.2 to 11.1.6.

6. Remove the threaded plug from the sampling point, insert the analyser probe and obtain the CO/CO2 ratio. This must be less than 0.004.

7. If the combustion reading is greater than this, and the integrity of the flue system and combustion circuit seals has

been verified, and the inlet gas pressure and gas rate are

satisfactory either adjust the gas valve (Section 11.0), replace the gas valve (Section 10.8)or contact the ‘heateam’ Technical Helpline (0844 871 1555).