Saunier Duval Thelia 23 PCB Ref. 05712700
When you open the tap or turn on the heating, the Saunier Duval Thelia 23 PCB controls the ignition, the modulation of the burner, the pump, and the safety features of the boiler. If it fails, you will notice that the boiler does not start, gets locked, or exhibits erratic behavior, potentially displaying fault codes such as F.28 or F.63. This board is compatible with models from the Thelia range, including the 23 (post-CE), 623, and AS 23 (post-CE), among others. A technician must confirm through diagnosis whether it needs to be replaced when these symptoms or fault codes occur.
- Type of part
- PCBs (control boards)
- Status
- Refurbished
- Catalogue reference
- 05712700
- Warranty
- 1 year
Saunier Duval boilers compatible with reference 05712700
PCB with reference 05712700. Four confirmed compatibilities: 23 (post-CE) and 623.
Proven compatibility
| Boiler model | Family | Verification |
|---|---|---|
| Saunier Duval 23 (post-CE) | Thelia | Contrasted |
| Saunier Duval 623 | Thelia | Contrasted |
| Saunier Duval 623 CE | Thelia | Contrasted |
| Saunier Duval AS 23 (post-CE) | Thelia | 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. 05712700 is the part for your boiler
The part reference, model, and equipment revision must be verified against the manufacturer's documentation.
- Find the reference printed on the installed part and check whether it matches the catalogue reference 05712700. 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 that require diagnosis on the PCB 05712700
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 is unresponsive, neither indicators nor controls are working: it seems dead.
Cause: The 80 mA T fuse on the PCB has blown and cuts off the power to all the electronics.
Measure with a multimeter if the 80 mA T fuse is blown before declaring the PCB (control board) as unusable; sometimes it is enough to just replace it.
- 02
The PCB gives the command, but the pump or the gas valve do not move.
Cause: The RYA30024 relays get stuck or burn out with use and stop transmitting the command even though the control works.
Listen for the click of the relay when requesting heating; if you don't hear it, first suspect the relay.
- 03
The boiler fails intermittently, sometimes it ignites and sometimes it doesn't, without a clear pattern.
Cause: It is a typical symptom in older manufactured PCBs, where solder joints and components degrade over years of service.
Note under what conditions it fails (cold, humidity, after several hours of being on) to rule out an external cause to the PCB.
- 04
The remote control or the thermostat cannot manage the boiler.
Cause: If the control section of the PCB is damaged, the boiler stops interpreting the commands it receives.
Do not force, hit, or bridge the component. Request a technical check according to the equipment manual before deciding on its replacement.
Fault codes Saunier Duval that require diagnosis
| Code | Fault | Technical checks |
|---|---|---|
| F.63 | EEPROM fault. | The EEPROM memory of the PCB is corrupted or unreadable; the self-diagnosis locks the equipment. Verify by measuring the power supplies of the PCB and, if the peripherals are correct, confirm by reprogramming/initializing or replacing the PCB. |
| F.64 | Fault in the electronics / NTC. | The analogue-to-digital converter or the measurement stage of the PCB misinterprets the NTCs (incoherent readings). Verify the actual resistances of the NTC at the board connector and the continuity of the harness; if they are correct and the fault persists, the PCB is faulty. |
| F.70 | Invalid product code (DSN). | After replacing the display and/or PCB, the DSN has not been recoded or there are missing/errors in the coding resistor; the board goes into lockout. Check the appliance code in the service menu and recode (d.93) or install the correct resistor/code. |
| F.61 | Gas valve control/activation fault. | The PCB driver does not deliver the appropriate signal/voltage to the gas valve (or detects it as short-circuited). Check the continuity of the harness and the command voltage/waveform at the valve terminals during the ignition attempt; if the valve and wiring are fine and there is no correct command, the cause is the PCB. |
| F.28 | Start-up fault: ignition failed. | If the ignition/control stage of the PCB fails (does not excite the spark transformer or does not switch the valve), the burner does not start and F.28 appears. Check the spark and control voltage to the transformer/valve; if gas, electrodes, and harnesses are OK and there is no excitation from the PCB, the cause is the PCB. |
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 05712700 PCB.
- Catalogue reference
- 05712700
- Uniclima internal SKU
- PLSA115
- Brand
- Saunier Duval
- Type of part
- PCBs (control boards)
- Units in stock
- 7 units
- Status
- Refurbished
- Warranty
- 1 year
- Shipping
- Delivery time shown at checkout
- Return
- 14 days
Part data and available documentation
Contrast the label codes, PCB, and revision with the installed part; they are not necessarily equivalent references.
- PCB code
- 8/050149D
- Manufacturing date
- 96/01/29
- Batch
- MTLC 9628
- Fuse
- 80mA T
- Supply voltage
- 230V
- Main relays (REL7/REL4/REL3)
- RYA30024 (x3)
- Relay - coil voltage
- 24V DC
- Relay - contacts
- 8A / 250V~ / AC1
- IC1
- LM350N (adjustable regulator)
- IC5
- LM393N (dual comparator)
- IC7
- MC14541BCP (programmable timer)
Manuals and technical documentation
Official documentation of the boiler, useful for locating the part and cross-referencing the fault codes.
- Saunier Duval 23 Manual (post-CE) (PDF) Document © Saunier Duval, provided as a technical reference.
Frequently asked questions about the PCB 05712700
Does this PCB 05712700 work for my Saunier Duval Thelia 23?
What fault of the Thelia 23 does this PCB resolve?
What relays are mounted on the PCB 05712700?
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