DeDietrich INIDENS 20/24 MI, Installation And Service Manual, Page: 202 / 352

10.4 Specific maintenance operations
10.4.1 Detection/ignition electrode replacement
Replace the detection//ignition electrode in the following cases:
1. Ionisation current <4 μA. To do this, activate the "chimney sweep function" (chapter "Combustion settings") and set the
boiler to the minimum power. The ionisation value is visible with setting GM008 (chapter "Reading out measured values").
2. Electrode worn.
3. Distances out of range (chapter “Electrode distance”).
To remove the electrode:
Disconnect the power supply to the boiler.
Cut off the gas supply to the boiler.
Remove the front panel on the boiler (case) and remove the electrode pin and the earthing cable.
Unscrew the 2 screws on the ignition electrode and remove it.
Fit the new electrode with the gasket. To re-assemble, perform the above actions in reverse order.
10.4.2 Dismantling the water-water exchanger
The stainless steel plate water-water heat exchanger can be easily removed, as described below:
1. Disconnect the power supply to the boiler;
2. Close the gas cock;
3. Close the heating system return and flow cocks.
4. Drain the system, if possible only the boiler, using the specific drain cock (E);
5. Empty the water contained in the domestic water circuit by opening a user cock;
6. Remove the silencer, then loosen the two Allen screws Ø 6 mm (A) securing the heat exchanger and remove it from its
seat;
7. Clean the plate heat exchanger using a natural product (e.g. vinegar) and a descaling agent (e.g. formic acid or citric acid
with a pH value of around 3);
8. To re-assemble, perform the above actions in reverse order.
Caution
The maximum tightening torque for the two fastening screws (A) for the plate heat exchanger is 4 Nm.
See also
Water treatment, page 161
10.4.3 Replacing the 3-way valve
If the 3-way valve must be replaced, proceed as follows:
1. Disconnect the power supply to the boiler;
2. Close the gas cock;
3. Close the heating system return and flow cocks;
4. Drain the system, if possible only the boiler, using the specific drain cock (E);
5. Disassemble the 3-way valve motor (C), removing the fastening clip (1) and extract the motor (2);
6. Remove the clip (3) and extract the 3-way valve (4);
7. For the "Heating only" boiler model, loosen the 3–way valve (4) from the hydraulic block;
8. Replace the 3-way valve;
9. To re-assemble, perform the above actions in reverse order.
10.4.4 Replacing the expansion vessel
Before replacing the expansion vessel, proceed as detailed below:
1. Disconnect the power supply to the boiler.
2. Close the gas cock.
3. Close the main domestic water tap.
4. Close the heating system return and flow cocks.
5. Open the boiler drain cock (E).
The expansion vessel is inside the boiler on the side, to the right.
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10 Maintenance
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