Saunier Duval Themafast F25 E Air Pressure Switch Ref. 605.99534
Air pressure switch for Saunier Duval boilers from the Isofast, Isomax, Isotwin, Opalia, Themaclassic, and Themafast series. It controls the pressure generated by the fan before allowing the burner to ignite. The label shows code 605.99534, with a switching setpoint of 59/51 Pa and electrical rating 1(0.5)/250~. It is replaced when it does not switch and the boiler locks out when the fan starts.
VAT included
Consult via WhatsAppSaunier Duval boilers compatible with reference S5744100
Pressure switch with reference S5744100. 21 verified compatibilities: F 30 E H-MOD and F 35 E1.
Proven compatibility
| Boiler model | Family | Verification |
|---|---|---|
| Saunier Duval F 30 E H-MOD | Isofast | Contrasted |
| Saunier Duval F 35 E1 | Isofast | Contrasted |
| Saunier Duval F 35 E H-MOD | Isofast | Contrasted |
| Saunier Duval F 28 E2 | Isomax | Contrasted |
| Saunier Duval F 28 EA | Isotwin | Contrasted |
| Saunier Duval F 30 E H-MOD | Isotwin | Contrasted |
| Saunier Duval F 30 E | Isosplit | Contrasted |
| Saunier Duval F 35 E | Isosplit | Contrasted |
| Saunier Duval F 35 E H-MOD | Isosplit | Contrasted |
| Saunier Duval F 25 E | Themafast | Contrasted |
| Saunier Duval F 25 E H-MOD | Themafast | Contrasted |
| Saunier Duval F 30 E | Themafast | Contrasted |
| Saunier Duval F 30 E H-MOD | Themafast | Contrasted |
| Saunier Duval F 25 E | Thema | Contrasted |
| Saunier Duval F 25 E STL | Thema | Contrasted |
| Saunier Duval F AS 25 E | Thema | Contrasted |
| Saunier Duval F 25 E | Themaplus | Contrasted |
| Saunier Duval F 30 E | Themaplus | Contrasted |
| Saunier Duval F AS 30 E | Themaclassic | Contrasted |
| Saunier Duval F 17 E | Opalia | Contrasted |
| Saunier Duval F 17 E | Opaliafast | 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. S5744100 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 S5744100. 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 pressure switch S5744100 resolves.
The pressure switch controls the air or water pressure to authorize operation. These are the typical symptoms and what to do:
Common symptoms and faults
- 01
The extractor is spinning, but the burner does not ignite and the boiler locks out with a fault warning.
Cause: The pressure switch does not close the contact that confirms that the extraction is correct and the gas does not activate.
Check that the external flue terminal is not obstructed, especially if the outlet is horizontal and short.
- 02
The boiler modulates strangely, abruptly increasing and decreasing power, and sometimes it locks itself.
Cause: A limit pressure switch may oscillate near its switching point when the fan changes speed during modulation.
Before replacing it, check that the modulating fan responds smoothly throughout its range, without jerks.
- 03
The extractor starts and stops repeatedly before the boiler completely locks out.
Cause: The retries of the control board are waiting for the signal from the pressure switch that is not arriving.
Check that the silicone tubes are not pinched by other components in a tight assembly, typical of compact boilers.
- 04
The fault is more frequent when it is very cold or there is a lot of condensation in the siphon.
Cause: The condensate water can reach the pressure take-off tubes if the siphon does not drain properly, leading to an incorrect reading of the pressure switch.
Check the siphon and the condensate drain before assuming that the pressure switch is faulty.
Fault codes from Saunier Duval that this spare part resolves.
| Code | Fault | Diagnosis and solution |
|---|---|---|
| 02 | Air flow safety. | The air pressure switch S5744100 does not switch when the fan starts or does not detect the depression due to obstruction in tubes/venturi; check with a multimeter or manometer that the pressure switch changes state with the fan running and inspect tubes and connections. |
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.
Datasheet for Saunier Duval pressure switch S5744100
- Catalogue reference
- S5744100
- Brand
- Saunier Duval
- Type of part
- Pressure switches
- 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.
- Component code
- 605.99534
- Switching pressure (setpoint)
- 59/51 Pa
- Electrical classification
- 1(0.5)/250~
- Internal code
- 116189
Manuals and technical documentation
Official documentation of the boiler, useful for locating the part and cross-referencing the fault codes.
- Saunier Duval F 25 E H-MOD Manual (PDF)Document © Saunier Duval, provided as a technical reference.
Frequently asked questions about the pressure switch S5744100
Is this air pressure switch suitable for the Saunier Duval Themafast F25 E?
What is the setting of the pressure switch for the Themafast F25 E?
Does this same pressure switch also work for the Isofast F30 or only for the Themafast F25 E?
What fault indicates that this pressure switch needs to be replaced in the Themafast F25 E?
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