Saunier Duval Isofast C 28 E Electronic Module Ref. 05721000
The Saunier Duval Isofast C 28 E electronic module is the control PCB that manages the ignition, burner modulation, pump, and safety features of the boiler. When it experiences faults, the boiler may fail to start, become locked, or operate erratically, potentially displaying fault codes such as F12, F18, or F13. This module is compatible with several models from the Isofast and Isomax ranges, including the C 28 E, C 35 E, and F 28 E, among others. It is recommended to replace the part when these malfunction symptoms are detected.
VAT included
Consult via WhatsAppSaunier Duval boilers compatible with reference 05721000
PCB with reference 05721000. 14 verified compatibilities: C 28 E and C 28 E1.
Proven compatibility
| Boiler model | Family | Verification |
|---|---|---|
| Saunier Duval C 28 E | Isofast | Contrasted |
| Saunier Duval C 28 E1 | Isofast | Contrasted |
| Saunier Duval C 28 E NOx | Isofast | Contrasted |
| Saunier Duval C 28 E1 NOx | Isofast | Contrasted |
| Saunier Duval C 35 E | Isofast | Contrasted |
| Saunier Duval C 35 E1 | Isofast | Contrasted |
| Saunier Duval F 28 E | Isofast | Contrasted |
| Saunier Duval F 28 E1 | Isofast | Contrasted |
| Saunier Duval F 35 E | Isofast | Contrasted |
| Saunier Duval F 35 E1 | Isofast | Contrasted |
| Saunier Duval C 28 E | Isomax | Contrasted |
| Saunier Duval C 28 E2 | Isomax | Contrasted |
| Saunier Duval F 28 E | Isomax | Contrasted |
| Saunier Duval F 28 E2 | Isomax | 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. 05721000 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 05721000. 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 05721000 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 doesn't light up any indicator, it's completely dead.
Cause: The module does not supply power to the rest of the circuits due to a fault in its power supply stage.
Check that 230V is reaching the boiler and that the main fuse has not blown before declaring the module faulty.
- 02
A fault code appears on the display that does not disappear after resetting.
Cause: The module locks the equipment upon detecting an unresolved safety condition.
Check which component that code indicates in the model's manual before replacing the entire module.
- 03
The boiler cycles on and off without a heat demand.
Cause: An output from the module intermittently gives incorrect commands.
Note if the pattern repeats consistently or is random: a fixed pattern points more towards an external component than the module.
- 04
The wall control has no communication with the boiler.
Cause: The communication stage of the module with the thermostat has stopped responding.
Check the bus wiring and, if possible, try another control before replacing the module.
Fault codes from Saunier Duval that this spare part resolves.
| Code | Fault | Diagnosis and solution |
|---|---|---|
| F12 | No signal from the user interface | Yes — it points to this display/interface module or its connection cable with the main PCB. |
| F18 | User interface fault | Yes — it corresponds to this display/control board module. |
| F13 | Main PCB fault | No — that code is for the MAIN PCB (a different part), not for this 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 05721000 PCB.
- Catalogue reference
- 05721000
- Brand
- Saunier Duval
- Type of part
- PCBs (control boards)
- Units in stock
- 5 units
- Status
- Refurbished
- Warranty
- 1 year
- Shipping
- 1-2 business days
- Return
- 14 days
Manuals and technical documentation
Official documentation of the boiler, useful for locating the part and cross-referencing the fault codes.
- Saunier Duval F 28 E Manual (PDF)Document © Saunier Duval, provided as a technical reference.
Frequently asked questions about the PCB 05721000
Is this module 05721000 suitable for an Isomax C 28 E?
Is this module also suitable for an Isofast C 24 E V1?
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