Saunier Duval Air Pressure Switch SD 623 Ref. 05156000
Air pressure switch Saunier Duval SD 623 Ref. 05156000 checks the air pressure in the boiler and allows it to operate correctly. If it fails, the boiler will not start or will lock out, even if the pressure is adequate, which can lead to fault codes F2 and F33. This model is compatible with Saunier Duval SD 623 and Duval Thelia 623 boilers, among others. A technician must confirm through diagnosis whether it is necessary to replace the pressure switch when you notice starting issues or lockouts in the boiler's operation.
Saunier Duval boilers compatible with reference 05156000
Pressure switch with reference 05156000. Two confirmed compatibilities: Duval SD 623 and Duval Thelia 623.
Proven compatibility
| Boiler model | Family | Verification |
|---|---|---|
| Saunier Duval Duval SD 623 | Saunier | Contrasted |
| Saunier Duval Thelia 623 | Saunier | 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 the ref. 05156000 is the part for your boiler
The part reference, model, and equipment revision must be verified against the manufacturer's documentation.
- Find the reference printed on the installed part and check whether it matches the catalogue reference 05156000. 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 that require diagnosis in the pressure switch 05156000
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 locks up on startup, the fan works but there is no gas.
Cause: The pressure switch does not close the circuit that confirms the flue gas exit, and the control board does not allow ignition.
Check the connection tubes of the pressure switch for any condensation or damage before replacing it.
- 02
Is the fault worse in winter or with intense cold?
Cause: The cold causes water to accumulate in the pressure switch tubes and affects the pressure reading.
Blow through the silicone tubes to see if any accumulated water comes out before replacing the part.
- 03
The fault warning turns off when disconnecting and reconnecting the boiler, but it reappears afterwards.
Cause: It is a symptom of a pressure switch that operates inconsistently and only provides a correct reading temporarily.
Note how long it takes for the fault to reoccur after each reset; this pattern helps to differentiate it from a flue problem.
- 04
The boiler works without the cover, but it fails when putting it back on.
Cause: It is possible that the pressure switch tube is pinched or disconnects when closing the casing.
Check the position of the silicone tubes with the cover on and off to see if there are any changes.
Fault codes Saunier Duval that require diagnosis
| Code | Fault | Technical checks |
|---|---|---|
| F2 | Safety Flue Test (SFT) / air pressure switch fault. | If the pressure switch does not switch on start-up, the PCB detects a lack of flue depression and locks out with SFT. Check silicone tubes/Venturi and the switching by applying controlled depression and measuring continuity at the contacts. |
| F33 | Airflow fault due to open/defective air pressure switch. | The pressure switch contact remains open or stuck, preventing the draft validation. Check with a vacuum pump/manometer and multimeter the triggering pressure and the closing/opening; inspect the venturi, flue duct, and fan to rule out obstructions. |
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.
Data sheet for the Saunier Duval pressure switch 05156000
- Catalogue reference
- 05156000
- Uniclima internal SKU
- PCSD623
- Brand
- Saunier Duval
- Type of part
- Pressure switches
- Units in stock
- 7 units
- Status
- Refurbished
- Warranty
- 1 year
- Shipping
- Delivery time shown at checkout
- Return
- 14 days
Frequently asked questions about the pressure switch 05156000
Is this part compatible with my Saunier Duval Thelia 623?
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