Saunier Duval Isofast F 35 EA Air Pressure Switch - Code 605.99534
The Saunier Duval air pressure switch, reference 605.99534, is responsible for verifying the air pressure in the boiler and authorizing its operation. If it fails, the boiler will not start or will lock out, even if the actual pressure is correct, which can lead to a fault code 02: Air flow safety. This component is compatible with boilers from the Isofast, Isomax, Isotwin, Isosplit, Themafast, and Thema ranges, among others. It is recommended to replace it when starting or locking issues are detected in the system.
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 boiler tries to ignite, turns off after a few seconds, and locks out.
Cause: If the pressure switch does not detect the extraction pressure in time, the control board cuts off the ignition for safety.
Check the condition of the flue gas outlet duct: an external obstruction can cause the same problem without the pressure switch being damaged.
- 02
The extractor works but the burner never ignites.
Cause: The pressure switch is the one that authorizes continuation after validating the draft; if it does not activate, the process stops.
Check that the connection pipes are not bent or disconnected at either end.
- 03
The fault appears and disappears: sometimes it ignites on the first try and other times it takes several attempts.
Cause: A worn or dirty contact can activate irregularly depending on the pressure it receives.
Clean and check the connections of the pipe before replacing the part, especially if the boiler has not had recent maintenance.
- 04
The boiler has been showing the same flue or pressure switch fault code for a while.
Cause: A repeated fault code of this type usually indicates that the pressure switch is no longer reliably closing the circuit.
Note the exact code that appears on the display before purchasing, to ensure that it corresponds to a fault of the pressure switch and not another sensor.
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.
- Part code
- 605.99534
- Set pressure (switching)
- 59/51 Pa
- Contact (current / voltage)
- 1(0.5) A / 250 V~
Manuals and technical documentation
Official documentation of the boiler, useful for locating the part and cross-referencing the fault codes.
- Saunier Duval F 35 E H-MOD Manual (PDF)Document © Saunier Duval, provided as a technical reference.
Frequently asked questions about the pressure switch S5744100
Is it the same pressure switch as the Isofast F 35 E, since they share the code 605.99534?
Is this pressure switch suitable for a Saunier Duval Themaclassic F 30 E?
At what pressure does the pressure switch of the Isofast F 35 EA switch?
Spare parts related to Saunier Duval Themafast
