Ignition Transformer Anstoss ZIG 2/12 Saunier Duval Themafast F25E Ref. S5742700
Ignition transformer for the Saunier Duval Themafast F25E boiler, manufactured by Anstoss Regelgeräte GmbH (Vienna, Austria), model ZIG 2/12, Art.Nr. 07000028. It operates at 300V/20kHz and withstands up to 80°C. It generates the high voltage that ignites the burner; it is replaced when the boiler fails to ignite due to a lack of spark or ignition arc.
VAT included
Consult via WhatsAppSaunier Duval boilers compatible with reference S5742700
Ignition transformer with reference S5742700. A verified compatibility: F25E.
Proven compatibility
| Boiler model | Family | Verification |
|---|---|---|
| Saunier Duval F25E | Themafast | 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. S5742700 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 S5742700. 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 ignition transformer S5742700 resolves.
The ignition transformer generates the high voltage for the spark of the electrodes. These are the typical symptoms and what to do:
Common symptoms and faults
- 01
A clicking or crackling sound is heard inside the transformer without a spark jumping at the electrode.
Cause: An internal arc in the transformer winding consumes the voltage before it reaches the electrode.
With the boiler turned off and unplugged, visually inspect the transformer for burn marks, cracks, or melted resin.
- 02
The spark appears, but it takes longer than usual to ignite after the fan starts.
Cause: A transformer that loses efficiency delays the generation of high voltage, and this delay can deplete the ignition safety time.
Time how long it takes for the spark to appear from when the fan starts and compare it with a unit in good condition if possible.
- 03
The ignition fault comes and goes: sometimes it ignites well and other times it locks out.
Cause: A transformer with partially damaged winding delivers inconsistent performance instead of failing consistently.
Check the condition of the high-voltage cable and its connection to the electrode, as a poor contact can also cause intermittent faults.
- 04
The ignition electrode is in good condition and properly positioned, but there is still no spark.
Cause: If the electrode and its distance are correct, the lack of arc directly points to the transformer as the most likely source.
Confirm the electrode gap distance (usually 3-4 mm) and ensure the ceramic is not cracked before concluding that the transformer is at fault.
Fault codes from Saunier Duval that this spare part resolves.
| Code | Fault | Diagnosis and solution |
|---|---|---|
| F.28 | Ignition fault code; it does not identify this transformer by itself. | Check whether a spark is present and verify the power supply, electrode, high-voltage cable, connector and appliance diagnostics before replacing the transformer. |
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.
Saunier Duval Ignition Transformer Datasheet S5742700
- Catalogue reference
- S5742700
- Brand
- Saunier Duval
- Type of part
- Transformers
- Units in stock
- 5 units
- 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.
- Manufacturer
- Anstoss Regelgeräte GmbH, Vienna, Austria
- Model / Art.Nr.
- ZIG 2/12, Art.Nr. 07000028
- Voltage / Frequency
- 300 V / 20 kHz
- Maximum temperature
- 80°C
- Certification
- VDE (triangular brand)
- Manufacturing date (batch)
- 04.OCT.04 (October 4, 2004)
- Batch
- 21952 00991132
- The compatibility of this spare part with the removed boiler was confirmed by checking the version, serial number, and connections.
Manuals and technical documentation
Official documentation of the boiler, useful for locating the part and cross-referencing the fault codes.
- Saunier Duval THEMAFAST F25E Manual (PDF)Document © Saunier Duval, provided as a technical reference.
Frequently asked questions about the ignition transformer S5742700
Who manufactures the ignition transformer for the Saunier Duval Themafast F25E?
What voltage does the ZIG 2/12 transformer of the Themafast F25E operate at?
What is the maximum temperature the ZIG 2/12 transformer of the Themafast F25E can withstand?
How do I confirm that this transformer is for my Themafast F25E?
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