Ignition Transformer ZIG 2/12 Saunier Duval 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.
Spare parts related to Saunier Duval Themafast
Saunier Duval boilers compatible with reference S5742700
Ignition transformer with reference S5742700. Compatibility confirmed with two independent sources: F25E. Verify the printed reference on your part before purchasing.
Compatibility confirmed
| Boiler model | Family | Verification |
|---|---|---|
| Saunier Duval F25E | Themafast | Confirmed · 2 sources |
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.
- Locate the reference printed on the body of the ignition transformer you have installed: it should indicate S5742700.
- Check your boiler model on the nameplate and look for it in the list of compatible models on this page.
- Compare the connections and the body with the original part before installing.
- If you have any doubts, send us a photo of the screen printing via WhatsApp and we'll confirm it for you before you purchase.
Symptoms and faults resolved by ignition transformer S5742700
The ignition transformer generates the high voltage for the spark of the electrodes. These are the typical symptoms and what to do:
A clicking or crackling sound is heard inside the transformer itself 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.
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.
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.
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.
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
- OEM 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
sources - Model / Art.Nr.
- ZIG 2/12, Art.Nr. 07000028
label+sources - Voltage / Frequency
- 300 V / 20 kHz
label - Maximum temperature
- 80°C
label - Certification
- VDE (triangular brand)
label - Manufacturing date (batch)
- 04.OCT.04 (October 4, 2004)
label - Batch
- 21952 00991132
label
- Check that the reference of your transformer matches ZIG 2/12 / Art.Nr. 07000028 before ordering it.
- The equivalent references 0020034711 and 2000801936 have been documented, but it is not clear how many independent sources support them; verify them as well before purchasing.
- The compatibility of this spare part with the removed boiler was confirmed by checking the version, serial number, and connections.