Expansion Vessel Saunier Duval Isofast F 30 EA Ref. S1025200
Saunier Duval presents the Isofast F 30 EA expansion vessel, a component that absorbs the increase in water volume when heated. When this part fails, you may notice that the boiler pressure fluctuates sharply, and the safety valve may start to leak. This expansion vessel is compatible with several models from the Isofast range, such as the Isofast F 30 E and the Isofast F 35 E H-MOD, among others. It is recommended to replace it when you observe these symptoms to avoid more significant issues in the system.
VAT included
Consult via WhatsAppSaunier Duval boilers compatible with the reference S1025200
Expansion vessel with reference S1025200. Five confirmed compatibilities: Isofast F 30 EA and Isofast F 30 E.
Proven compatibility
| Boiler model | Family | Verification |
|---|---|---|
| Saunier Duval Isofast F 30 EA | Saunier Duval | Contrasted |
| Saunier Duval Isofast F 30 E | Saunier Duval | Contrasted |
| Saunier Duval Isofast F 30 E H-MOD | Saunier Duval | Contrasted |
| Saunier Duval Isosplit F 30 E H-MOD | Saunier Duval | Contrasted |
| Saunier Duval Isofast F 35 E H-MOD | Saunier Duval | 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 part S1025200 is the one 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 S1025200. 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 expansion vessel S1025200 resolves.
The expansion vessel absorbs the expansion of water when heated. These are the typical symptoms and what to do:
Common symptoms and faults
- 01
The pressure suddenly rises as soon as the heating is turned on, even though it is correct when cold.
Cause: This indicates that the internal membrane of the vessel has broken, preventing it from acting as an air cushion, and the circuit behaves as if it does not have a vessel.
With the boiler cold, remove the cap from the Schrader valve of the expansion vessel and press the stem for a moment; if water comes out instead of air, the membrane is broken.
- 02
The circuit gradually loses pressure and needs to be refilled every few weeks.
Cause: The vessel has lost nitrogen charge or has a leak, so it no longer compensates for the expansion of water when heated, and the system is short on pressure.
Gently tap the glass on both halves with the boiler cold: if it sounds hollow evenly across the entire casing, it has lost the air precharge.
- 03
A knocking sound is heard in the pipes when opening the hot water or when starting the boiler.
Cause: Without the air cushion in the expansion vessel to absorb the flow change, that pressure surge is transmitted throughout the entire system.
Check for trapped air by bleeding the radiators before assuming it's the expansion vessel; the symptom is very similar.
- 04
The safety valve drips when the heating has been running for a while.
Cause: Without the expansion vessel, the pressure in the circuit rises until the safety valve is forced to relieve it.
Compare the cold pressure with the pressure after 15 minutes of operation: a strong and sustained increase indicates the expansion vessel, not the valve.
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.
Expansion vessel data Saunier Duval S1025200
- Catalogue reference
- S1025200
- Brand
- Saunier Duval
- Type of part
- Expansion vessels
- Units in stock
- 7 units
- Status
- Refurbished
- Warranty
- 1 year
- Shipping
- Delivery time shown at checkout
- Return
- 14 days
Manuals and technical documentation
Official documentation of the boiler, useful for locating the part and cross-referencing the fault codes.
- Saunier Duval Isofast F 30 E Manual (PDF)Document © Saunier Duval, provided as a technical reference.
Frequently asked questions about the expansion vessel S1025200
Is this expansion vessel suitable for the Isofast F30 EA?
What fault does changing this expansion vessel resolve?
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