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6. MAINTENANCE AND CLEANING
The following operations must be carried out by Corgi registered engineers only.
6.01 Annual Servicing
The following should be checked at least once a year:
Water pressure in the central heating system when cold should be
about 1 bar. If this is not the case, bring it back to this value.
Check control and safety devices (gas valve, thermostats, etc) are
functioning correctly.
The burner and heat exchanger must be clean. To avoid damage,
always clean them with a soft brush or compressed air. Never use
chemical products.
The expansion vessel (if fitted) must be checked.
Check there are no leaks in the gas and water circuits.
Check the air-flue gas duct terminal is free from obstructions and
sound.
The electrode must be free from corrosion build up and correctly
positioned (see fig. 44).
Gas flow and pressure must correspond to the values given in the
Technical Data (paragraph 1.03).
The pump must be free to rotate.
6.02 Cleaning the boiler and burner
The boiler should be serviced annually. Before starting check the boiler is operating correctly then isolate the electrical and
gas supply to the boiler. The heat exchanger may be cleaned by insertion of a thin metal strip e.g. a hack saw blade or steel
rule, from above or below. Clean the front and rear fin sections and ensure that any blockages are cleared.
The burner must never be cleaned with chemical products or steel brushes. Particular attention must be paid to all seals
and fixings associated with the room-sealed compartment (gaskets, grommets, etc). Air leakage would cause pressure
inside the compartment to drop, possibly tripping the differential pressure switch and thus shutting down the boiler. After
cleaning particular attention should also be paid to checking stages of start-up and operation of the thermostats, gas valve
and pump.
If performing combustion analysis prior to servicing, the CO/CO
required. After a full service the CO/CO
6.03 Sigma Servicing Procedure (only to carried out by a competent person)
1) Visually check the boiler for correct installation and flueing.
2) Isolate electricity supply.
3) Remove cover (2 screws at bottom light and pull forward).
4) Carry out preliminary electrical checks at the boiler junction box. This is situated to the right of the sealed
compartment and is accessed by lowering the control PCB compartment (1 screw).
Note: The boiler electrical supply will need to be isolated, whilst carrying out polarity checks. Any faults must be rectified
before proceeding.
5) If electrical checks prove o/k replace control panel and secure with fixing screw.
6) Using the inlet pressure test point on the gas valve check the inlet WORKING gas pressure, this should be 20 millibar
MINIMUM for N.G. and 37 millibar MINIMUM for LPG.
This should be available at all times i.e. when all other gas appliances from the same supply are working fully. If this
is not the case, installation may be deemed AT RISK and the gas supply pipework throughout the system may have
to be increased in size.
22
Sigma
ratio must not exceed 0.0008.
2
Electrode
Sectioned
burner
ratio must not exceed 0.0004. If it does, a full service is
2
Fig. 44
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