Ntc Flue Sensor; Flow And Return Sensors; Safety Overheat Thermostat; Hmi Control - Baxi COMBI 224 Installation And Service Manual

10 Maintenance
Fig.48 Removing the NTC flue sensor
Fig.49 Removing the flow and return sen­
sors
Fig.50 Removing the safety overheat ther­
mostat
Fig.51 HMI removal
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2
56

10.3.2 NTC flue sensor

1. Turn the sensor 90° anticlockwise to remove — it is a bayonet con­
2. Ease the retaining tab on the sensor away and disconnect the elec­
3. Fit new sensor and reassemble in reverse order.
PN-0000237

10.3.3 Flow and return sensors

There is one sensor on the flow (red wires) and one sensor on the return
(black wires).
1. Remove the air/gas unit.
2. After noting the position prise the sensor clip off the pipe and discon­
3. Connect the plug to the new sensor and ease the clip onto the pipe
PN-0000249

10.3.4 Safety overheat thermostat

1. Pull the two spade connections off the safety overheat thermostat.
2. Prise the thermostat clip with the safety overheat thermostat off the
3. Fit new safety thermostat on the pipe using heat-sink paste.
4. Connect the two spade connections to the safety overheat thermo­
PN-0000250

10.3.5 HMI control

1. Remove the screws from the link/timer
2. Hinge the control box downwards.
3. Disengage the optional timer plug and ease the cable out of its
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2
4. Unclip the back cover of the control box and remove it.
5. Unplug the wire harness on the HMI control.
6. Release the clips securing the HMI control and remove it.
7. Fit the new HMI control and reassemble in reverse order ensuring all
PN-0000287
nection.
trical plug.
See
To remove see Section 10.3.7 Air/gas unit.
nect the plug.
in its original position.
pipe
stat ensuring that they are pushed fully on.
housing.
plugs and cables are seated correctly.
Note
Ensure that wiring is correctly routed with no wires trapped during
reassembly.
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