Hamworthy Sherborne Series Installation, Commissioning And Servicing Instructions page 34

11.0 REPLACEMENT OF FAILED COMPONENTS
The components listed below can be replaced simply & quickly by the following procedures. Check the operation
of new components by carrying out the appropriate part of the commissioning procedure. See Section 7
NOTE: Isolate all electrical supplies to the boiler & turn off the gas supply before commencing any
Remove the screw on the bottom of the cover & pull the cover up & off the hooks on the wall frame.
11.1 Hot Surface Igniter & Flame Probe Assembly.
Note:- igniter & probe ceramics are fragile. Do not remove both as flange & sight glass will become detached.
Igniter
•
Unplug the igniter from the harness & remove the single socket cap head screw securing the igniter.
•
Withdraw the igniter, renew or clean as required & generally remove any
loose sooty deposits.
•
Replace igniter & secure socket cap head screw holding the igniter to the
burner flange.
•
Check igniter is correctly positioned in the bracket before assembly
Flame Probe Assembly
•
Disconnect the flame sensing probe connection.
•
Remove the single socket cap head screw securing the probe to the burner flange & withdraw the probe.
•
Renew or clean & generally remove any loose sooty deposits.
11.2 Flow / Return Sensor Part No. 533901431 (located in the flow & return pipes at the rear of the boiler)
•
Disconnect sensor plug from wiring harness & loosen the screw securing the sensor in the pocket.
•
Withdraw sensor from pocket & fit replacement, securing with the screw & re-connecting the plug.
11.3 Temperature Limiter (Limit Stat) Renewal. Part Nos. 533901179
Remove the 'push on' spade connections from the temperature
limiter body noting position of coloured cables. Remove the two
screws securing the thermostat to the display panel & withdraw
the capillary & bulb from the sensing pocket in the front of the
heat exchanger. Check the operation of the device by carefully
applying a heat source to the bulb. Set temperature limiter to
(maximum 100°C) & re-assemble temperature limiter ensuring
correct cable notation. Refer to Figure 9.3.2 for terminal
identification.
11.4 Main Gas Valve / Venturi Part No. 533903033
The gas valve & venturi are supplied as a matched & factory set assembly & must not be tampered with or
adjusted. To replace the gas valve/venturi it is preferable to remove the complete fan assembly.
•
Unplug the 2 connectors from the fan & gas valve.
•
Remove the screws securing the gas valve inlet elbow to the gas valve (take care not to loose the 'O' ring)
•
Disconnect the pressure feedback tube from the gas valve.
•
Remove the screws/nuts securing the fan/venturi/gas valve assembly to the transition duct.
•
Withdraw the assembly from the air inlet duct.
•
Remove the screws securing the venturi/gas valve assembly to the fan (note cork sealing gasket)
•
Remove the copper feedback connecting tube from the valve & refit to the new valve using thread sealant.
•
When replacing the gas valve it is advisable to renew the O-ring (See spares section for Part Nos).
•
In LPG boilers check the orifice plate is undamaged & fitted in the recess in the gas valve. (Refer fig 11.4).
•
Re-assemble using new gaskets where necessary & ensuring correct orientation of gas valve.
•
Ensure electrical plugs are firmly & correctly located.
•
Switch on gas & power supply & check for integrity of all joints using a proprietary leak detector.
•
Ensure gas valve operation is correct & safe before continuing.
•
Re-light the boiler
•
Check & adjust the combustion as detailed in Section 7
11.5 Fan Assembly Part No. 563901376
To replace the fan it is preferable to remove the complete gas valve/venturi & fan assembly.
HAMWORTHY HEATING LTD
servicing or component exchange procedure.
SHERBORNE
Part Nos. 563801011 & 533805019
Temp °C
0
10
20
30
40
32
Resistance Ω Temp °C Resistance Ω
41505 50
19691 60
12474 70
8080 80
5372 90
500001167/E
3661
2536
1974
1290
942