Saunier Duval PCB SD 623 Combi Ref. 05159600
PCB for the Saunier Duval SD 623 Combi boiler, service reference 05159600. It includes a transformer identified as Saunier Duval Nº 8/411026 (220V 50Hz on the primary side, 24V/13VA on the secondary side, protected by an 80 mA T thermal fuse), two Schrack RP420024 relays, and a 400 µF - 250V capacitor. It is replaced when the control electronics fail and the boiler stops responding.
VAT included
Consult via WhatsAppSaunier Duval boilers compatible with reference 05159600
PCB with reference 05159600. Seven confirmed compatibilities: SD 623 and SD 623 Combi.
Proven compatibility
| Boiler model | Family | Verification |
|---|---|---|
| Saunier Duval SD 623 | SD 623 / Thelia 623 (Combi) | Contrasted |
| Saunier Duval SD 623 Combi | SD 623 / Thelia 623 (Combi) | Contrasted |
| Saunier Duval Thelia 623 | SD 623 / Thelia 623 (Combi) | Contrasted |
| Saunier Duval Thelia 623E | SD 623 / Thelia 623 (Combi) | Contrasted |
| Saunier Duval Thema 23 | Thema / Themis 23 (equivalent family of the same chassis 623) | Contrasted |
| Saunier Duval Themis 23E | Thema / Themis 23 (equivalent family of the same chassis 623) | Contrasted |
| Saunier Duval Themis 623E | Thema / Themis 23 (equivalent family of the same chassis 623) | Contrasted |
Can't see your model or have questions? The printed reference takes precedence. How to check it · Send us a photo via WhatsApp.
How to check if ref. 05159600 is the part for your boiler
What determines it is not the boiler model, but the reference printed on the part you already have installed.
- Find the reference printed on the installed part and check whether it matches the catalogue reference 05159600. If it is not visible, do not identify the part from its shape alone.
- Check the full boiler model on its data plate and look for it in the model associations on this page.
- Compare the connections and physical body with the original part before installation.
- If anything is unclear, send us a photo of the marking via WhatsApp before placing your order.
Symptoms and faults that the PCB 05159600 resolves.
The PCB controls the ignition, modulation, and safety features of the boiler. These are the typical symptoms and what to do:
Common symptoms and faults
- 01
The boiler does not turn on, there are no lights and it does not respond to anything.
Cause: The 80 mA thermal fuse of the transformer may have blown, cutting off power to the entire control electronics.
Unplug the boiler and measure the continuity of the thermal fuse of the transformer before replacing the PCB.
- 02
The burner, the pump, or the gas valve are not working even though the control board is requesting heat.
Cause: The Schrack RP420024 relays may be stuck or burned out and do not transmit the control signal.
Listen for the click of the relay when starting the demand; if you don't hear it, it's a clear indication before replacing the PCB.
- 03
The boiler starts irregularly: sometimes it ignites and sometimes it doesn't.
Cause: A faulty start capacitor (400 µF - 250V on this PCB) causes irregular starts.
If the fault is random and does not always repeat in the same way, note it down: it is a typical pattern of a capacitor, not a fixed fault.
- 04
The boiler starts but shuts down after a few seconds for no apparent reason.
Cause: The PCB may not maintain a stable control signal to the rest of the components after the first impulse.
Make sure that the transformer connection to the PCB is secure and free of oxidation before considering the board as faulty.
Fault codes from Saunier Duval that this spare part resolves.
| Code | Fault | Diagnosis and solution |
|---|---|---|
| F11 | No signal is reaching the main circuit. | The control/display PCB (user interface) is not communicating with the main PCB due to a fault in the interface itself or its wiring/connection. Verify by measuring power supply to the interface and continuity of the harness/flat cable, and test with a known interface or by reconnecting the UI–PCB connector. |
| F12 | No user interface signal. | The control/display board does not send a signal (or does not receive it) due to a fault in the interface or a poor connection between the interface and the main board. Check the 5 V/12 V power supply to the interface, inspect/clean the UI–PCB connector, and if the issue persists, replace the interface. |
| F18 | User interface fault. | Internal fault of the control/display PCB causing lockout or erratic readings. Check with reset and measure interface voltages; if it does not respond or the fault recurs, replace the interface PCB. |
| F20 | Software interface incompatible with the model. | User interface (display board) incompatible or improperly configured after replacement, causing the main board to reject the identification. Verify the code/product and reconfigure/update; if incorrect, install the compatible interface/display. |
These symptoms can have more than one cause. If your boiler displays a fault code, send it to us via WhatsApp along with a photo of the labeling, and we'll tell you if this is the part.
Data sheet for the Saunier Duval 05159600 PCB.
- Catalogue reference
- 05159600
- Brand
- Saunier Duval
- Type of part
- PCBs (control boards)
- Units in stock
- 1 unit
- Status
- Refurbished
- Warranty
- 1 year
- Shipping
- 1-2 business days
- Return
- 14 days
Data read on the part and in the manufacturer's documentation
What we have not been able to verify does not appear here.
- Transformer - primary voltage
- 220V 50Hz
- Transformer - secondary voltage
- 24V, 13VA
- Transformer - thermal protection
- 80mA T, class T50/E
- REL1/REL2 relays
- Schrack RP420024, 24V=, 8A/250V~AC1, Made in Austria
- Condenser
- 400µF - 250V, HP T
- Transformer identification
- Saunier Duval No. 8/411026
Manuals and technical documentation
Official documentation of the boiler, useful for locating the part and cross-referencing the fault codes.
- Saunier Duval SD 623 Manual (PDF)Document © Saunier Duval, provided as a technical reference.
Frequently asked questions about the PCB 05159600
Is this PCB suitable for an SD 623 that is not a Combi?
What relays does the PCB of the Saunier Duval SD 623 Combi have?
What protection does the transformer of this PCB for the SD 623 have?
What capacitor does the PCB Ref. 05159600 use?
Spare parts related to Saunier Duval SD 623 / Thelia 623 (Combi)
