Saunier Duval Isofast F 28 E1 Air Pressure Switch Ref. 605.99523
Air pressure switch for Saunier Duval boilers from the Isofast, Isomax, Isotwin, Opalia, and Thema ranges. It controls the differential pressure of the flue gas extraction circuit and allows ignition only if it detects correct draft. It is factory set to 54/46 Pa (open/close) and supports up to 1(0.5) A at 250 V~. It is replaced when the boiler locks out due to a pressure switch fault or does not detect extraction.
VAT included
Consult via WhatsAppSaunier Duval boilers compatible with reference S5744000
Pressure switch with reference S5744000. Two confirmed compatibilities: Isofast F 28 E and Isofast F 28 E1.
Proven compatibility
| Boiler model | Family | Verification |
|---|---|---|
| Saunier Duval Isofast F 28 E | Isofast | Contrasted |
| Saunier Duval Isofast F 28 E1 | Isofast | 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. S5744000 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 S5744000. 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 S5744000 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, the fan can be heard, but it stops and shows a fault related to air or flue.
Cause: The pressure switch does not close the contact that allows the gas to flow, so the control board cuts off the ignition for safety.
Check that the silicone tube going from the pressure switch to the flue is not bent, disconnected, or has accumulated water.
- 02
The extractor works normally, but the boiler does not ignite the burner.
Cause: If the pressure switch does not detect sufficient negative pressure even though the fan is running properly, the control board interprets that there is no draft and blocks the ignition.
Check that the flue gas outlet to the outside is not obstructed by snow, ice, leaves, or a nest before replacing the part.
- 03
The boiler intermittently locks out, working some days and not others.
Cause: The pressure switch membrane loses accuracy with use and responds irregularly to small pressure variations.
Note if the fault coincides with days of strong wind or rain, as this affects the actual draft of the flue.
- 04
After a power outage or a long stop, the boiler does not restart on its own.
Cause: If the pressure switch connection tubes have come loose or the connector has become loose, the pressure reading becomes invalid.
Check that the electrical connectors of the pressure switch are properly fitted and free of corrosion before replacing it.
Fault codes from Saunier Duval that this spare part resolves.
| Code | Fault | Diagnosis and solution |
|---|---|---|
| 02 | Airflow/flue fault (flue safety). | The air pressure switch does not switch when the fan starts (damaged diaphragm/contacts, obstructed intake tubes, or poor connection), so the PCB detects a lack of pressure drop and triggers the air fault; verify by measuring the continuity of the pressure switch (Pr terminals) with a multimeter during startup, and check the pressure and exhaust tubing. |
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 the Saunier Duval pressure switch S5744000
- Catalogue reference
- S5744000
- 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.
- Set (opening/closing)
- 54/46 Pa
- Electrical contact
- 1(0.5) A / 250 V~
- Part code
- 605.99523
- Batch
- 115830
- Manufacturing date
- 12/01
- Production batch code
- YJXBCB
Frequently asked questions about the pressure switch S5744000
What reference should the air pressure switch of the Saunier Duval Isofast F 28 E1 have?
At what pressure does the pressure switch of the Isofast F 28 E1 open and close?
Is this pressure switch compatible with other Saunier Duval models?
What fault indicates that the air pressure switch of the Isofast F 28 E1 needs to be replaced?
How many models are compatible with the air pressure switch 605.99523?
What fault code is documented for this pressure switch?
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