Ideal Boilers Optia HE 9 Installation And Servicing Instructions

36 Optia HE - Installation & ServicingSERVICINGcla774264 THERMOSTAT CONTROL, THERMISTOR SENSOR LEAD & ON/OFF SWITCHREPLACEMENTRefer also to Frame 61.A. Remove the control box fixing screwsB. Swing the control box down into the servicing position.Thermostat control1. Pull the knob off the shaft.2. Remove the backnut securing the thermostat control to the controlbox.3. Pull off the Molex connector from the printed circuit board.4. Replace and reassemble in reverse order.Thermistor sensor lead5. Pull the sensor lead connector off the printed circuit boardand cut the cable strapsecuring the thermistorharness to the bottom panelof the control box (if fitted) andremove the strap.6. Remove the sensor from theheat exchanger pocket andunclip from the casing.7. Remove the strain relief bushfrom the back panel base.8. Remove the sensor leadthrough the grommet in thecontrol box.9. Replace and reassemble inreverse order, ensuring thenew cable strap is fitted andsecuring the thermistorharness.On/off switch10. Disconnect the electrical connectorsfrom the rear of the switch.11. Press in the 2 side retaining clips and remove theswitch.12. Reassemble in reverse order.1. Refer to Frame 61.2. Remove the control box fixing screws.3. Swing the control box down into the servicing position.63 OVERHEAT THERMOSTAT REPLACEMENTcla78494. Pull off the electrical connections at the thermostat. Removethe backnut retaining the thermostat to the casing. Withdrawthe thermostat phial from the heat exchanger pocket andunclip from the casing.5. Fit the new thermostat and reassemble in reverse order.6. Check the operation of the boiler.SERVICING