Saunier Duval ThemaClassic F 24 Air Pressure Switch - Ref. S1008900 (605.99561)
Air pressure switch that checks the proper functioning of the extractor/fan before allowing the burner to ignite. If it does not detect the switching depression within the set range, the boiler locks out for safety. Replacement requires first confirming the fault of the part through technical diagnosis, even when the burner does not start despite the extractor running normally, or the contact does not switch.
- Type of part
- Pressure switches
- Status
- Refurbished
- Catalogue reference
- S1008900
- Warranty
- 1 year
Saunier Duval boilers compatible with reference S1008900
Pressure switch with reference S1008900. Seven confirmed compatibilities: ThemaClassic F24 E and ThemaClassic F25 E.
Proven compatibility
| Boiler model | Family | Verification |
|---|---|---|
| Saunier Duval ThemaClassic F24 E | ThemaClassic | Contrasted |
| Saunier Duval ThemaClassic F25 E | ThemaClassic | Contrasted |
| Saunier Duval ThemaClassic F AS 24 E | ThemaClassic | Contrasted |
| Saunier Duval ThemaClassic F AS 25 E | ThemaClassic | Contrasted |
| Saunier Duval Thematek SF 24 E | Thematek | Contrasted |
| Saunier Duval Thematek F 24 E | Thematek | Contrasted |
| Saunier Duval Combitek F24 E | Combitek | 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. S1008900 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 S1008900. 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 S1008900
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 burner does not ignite even though the air extractor is functioning normally.
Cause: The pressure switch does not detect the correct depression, so the control board blocks the gas flow for safety.
Check that the silicone tubes of the pressure switch are properly connected and free of condensate before replacing it.
- 02
The boiler stops during the pre-purge or ventilation phase, without attempting ignition.
Cause: The control unit needs the correct signal from the pressure switch in that phase; if it doesn't arrive, it cuts off before supplying gas.
Check at what exact moment in the cycle the boiler stops: if it always stops at the same point, it points more to the pressure switch than to another part.
- 03
The blockage is attributed to the air pressure switch, but the fan seems to be working fine at first glance.
Cause: The internal contact of the pressure switch may be open due to wear or breakage, even if the depression generated by the fan is correct.
Before changing the part, visually check that the fan is spinning cleanly, without any unusual noises or vibrations.
- 04
The boiler ignites intermittently, sometimes working well and other times it locks out for no apparent reason.
Cause: A contact that switches irregularly due to wear can cause faults that do not always occur at the same time.
Keep a simple log of when the fault occurs (time, whether it has just started or has been running for a while) to rule out external causes before replacing the part.
Fault codes Saunier Duval that require diagnosis
| Code | Fault | Technical checks |
|---|---|---|
| F2 | Air deficiency safety (Themaclassic F): flue gas intake/exhaust fault. | The air pressure switch does not switch (does not close) when the fan starts due to lack of depression, fatigued diaphragm, or blocked inlets/tubes; check continuity at its terminals during the pre-purge and inspect tubes to the fan and flue duct. |
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 S1008900
- Catalogue reference
- S1008900
- Uniclima internal SKU
- PSDTF24
- 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
Part data and available documentation
Contrast the label codes, PCB, and revision with the installed part; they are not necessarily equivalent references.
- Model code
- 605.99561
- Set (switching/reset)
- 80/68 Pa
- Switching value of the contact
- 1(0.5)/250~
- Long code (likely internal ref. Saunier Duval/Vaillant)
- 4000121232
- Batch code
- N11CIB
- Date (week/year)
- 28/01
Manuals and technical documentation
Official documentation of the boiler, useful for locating the part and cross-referencing the fault codes.
- Saunier Duval ThemaClassic F AS 25 E Manual (PDF) Document © Saunier Duval, provided as a technical reference.
Frequently asked questions about the pressure switch S1008900
Is this pressure switch compatible with the ThemaClassic F24 E?
Is the pressure switch of the ThemaClassic F24 E for air or flue gases?
At what pressure does the pressure switch of the ThemaClassic F24 E switch and reset?
When should the pressure switch of the Thematek SF24 E be replaced if the fan is operating normally?
How many models are compatible with this pressure switch?
What is the reference for the Saunier Duval air pressure switch?
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