Bosch Appliances 24I RSF manual Spark electrode assembly

6. Combustion Chamber Insulation.

Check that the electricity supply to the appliance is turned off. Drain the central heating circuit as described in Section 15.3(a). Remove the inner casing cover, fan, flue hood assembly, burner, and Gas to Water heat exchanger as described in Sections 14.3 (b, e and f), and 15.4 (5). Remove the fibre insulation pads from the combustion chamber side, rear, and front sections.

Fit the replacement pads in the reverse order taking care not to damage them.

Open the valves and fill and re-pressurise the system as described in Section 12.2.

7.Burner. See Fig. 31.

Check that the electricity and gas supplies to the appliance are turned off.

Remove the burner assembly as described in Section 14.3 (h).

Fit the replacement burner in the reverse order taking care not to damage the electrode leads.

8. Burner Injector. See Fig. 31.

Remove the burner as described in Section 14.3 (h). Unscrew the brass injector from the manifold.

Fit the replacement injector in the reverse order.

9. Spark Electrode Assembly. See Fig. 31a.

Remove the combustion chamber front as described in 14.3 (g) Carefully pull off the two electrode leads,

Undo the M4 extended nut and remove the spark electrode assembly from the burner.

Fit the replacement electrode in the reverse order, checking that the spark gap is 3.5 to 4.5mm.

Fig. 31a. Spark electrode assembly.

3.5-4.5mm

2.5-5mm

10. Flame Sensor. See Fig. 31.

Remove the burner as described in sections 14.3(h) and 15.4(8). Undo the M3 screw and remove the sense electrode from the burner.

Fit the replacement electrode in the reverse order, checking that the sense gap is 5 to 6mm.

11.Gas Valve. See Figs. 33. and 34.

Check that the electricity and gas supplies to the appliance are turned off.

Hinge down the control box assembly in the servicing position as described in Section 14.3(d).

Whilst supporting the valve unscrew the plug retaining screw and carefully pull off the electrical solenoid plug connection and the two modureg leads.

Undo the 8 manifold screws and remove the gas valve. See Fig. 34. Fit the replacement gas valve in the reverse order ensuring the ÒOÓ rings are correctly fitted.

Turn on the gas supply and check for soundness. To set the burner pressure. See Fig. 33.

The minimum and maximum burner pressures must be set after a new gas control has been fitted.

The maximum burner pressure must be set first, as any adjustment of the maximum pressure influences the minimum pressure setting.

Start the appliance in the domestic hot water mode as described in section 12.4. - Appliance Operation.

Adjust the maximum pressure adjustment screw on the gas valve to give a burner pressure of 13.6 mbar on natural gas, for propane the maximum pressure adjustment must be increased to maximum clockwise, this should give 33.0 - 35.0 mbar.

End the demand and reset the appliance by interrupting the mains electricity supply. (Otherwise there is a four minute anti- cycle delay at the end of a demand).

Restart the appliance in central heating mode and adjust the minimum adjustment screw on the gas valve to give a pressure of 1.0 mbar on natural gas or 3.5 mbar on propane. See Fig. 33.

After completing the adjustments, check the minimum and maximum pressures and re-adjust as necessary. Once this has been done the clear cap should be re-fitted to the adjuster and the retaining screw tightened. Coat the screw with paint or nail varnish to prevent user adjustment.

Fig. 27. Gas valve.

		Maximum pressure
Main gas valve		adjuster
	Minimum	Note: Clockwise to
connections
	pressure	increase and anti-
(Black : blue : brown :
	adjuster	clockwise to
green/yellow)
		decrease the
		pressure
Burner pressure
test point

Inlet pressure test point

Modulating	Electrical connections Ð
	modulator (Blue : Blue)
solenoid

12. Central Heating Sensor. See Fig. 34.

Check that the electricity supply to the appliance is turned off. Hinge the facia assembly in the servicing position as described in Section 14.3(c and d).

Carefully pull off the two leads from the sensor.

Pull off the sensor and spring retaining clip from the pipe.

Fit the replacement sensor in reverse order with a layer of heat sink compound between the faces. Refit the leads.

Fig. 34. Gas valve pump and air pressure

switch.		Air pressure switch
Top gas valve	Gas	Pump connecting tubes
connection (4 bolts)	valve

Red pipe

	Central Heating	Pressure gauge
Gas valve	Sensor	connection
electrical	Lower pump		Air pressure
connections	connection		switch

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