Three-Way Valve Saunier Duval Isofast, Isomax and Other Ranges - Ref. S1025500
The Saunier Duval Isofast, Isomax, and other ranges 3-way valve - Ref. S1025500, is a device that switches water between the heating circuit and the domestic hot water circuit. When it fails, you may notice that there is hot water but no heating, or both circuits may mix, which can trigger the fault code F.20: safety disconnection due to temperature limiter. This valve is compatible with boilers such as F 35 E-A, F 30 E-A, C 35 E-A, among others from the Isofast, Isomax, Isotwin, and Themafast ranges. A technician must confirm through diagnosis whether it is necessary to replace it when the mentioned symptoms occur or when detecting a malfunction in the heating or hot water.
- Type of part
- 3-way valves
- Status
- Refurbished
- Catalogue reference
- S1025500
- Warranty
- 1 year
Saunier Duval boilers compatible with reference S1025500
3-way valve with reference S1025500. 18 verified compatibilities: F 35 E-A and F 30 E-A.
Proven compatibility
| Boiler model | Family | Verification |
|---|---|---|
| Saunier Duval F 35 E-A | Isofast | Contrasted |
| Saunier Duval F 30 E-A | Isofast | Contrasted |
| Saunier Duval C 35 E-A | Isofast | Contrasted |
| Saunier Duval F 35 E H-MOD | Isofast | Contrasted |
| Saunier Duval F 30 E H-MOD | Isofast | Contrasted |
| Saunier Duval Condens F 30 E | Isofast | Contrasted |
| Saunier Duval Condens F 35 E | Isofast | Contrasted |
| Saunier Duval F 35 E | Isomax | Contrasted |
| Saunier Duval F 35 H-MOD | Isomax | Contrasted |
| Saunier Duval Condens F 35 E | Isomax | Contrasted |
| Saunier Duval F 30 H-MOD | Isotwin | Contrasted |
| Saunier Duval Condens F 30 E | Isotwin | Contrasted |
| Saunier Duval F 25 E | Themafast | Contrasted |
| Saunier Duval F 30 E | Themafast | Contrasted |
| Saunier Duval C 25 E | Themafast | Contrasted |
| Saunier Duval C 30 E | Themafast | Contrasted |
| Saunier Duval Condens F 25 | Themafast | Contrasted |
| Saunier Duval Condens F 30 | Themafast | 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. S1025500 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 S1025500. 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 3-way valve S1025500
The 3-way valve diverts water between heating and domestic hot water. These are the typical symptoms and what to do:
Common symptoms and faults
- 01
The tap water comes out lukewarm or cold while the radiators are working well, or vice versa.
Cause: The valve is not directing the water correctly to the corresponding circuit.
Measure the temperature in each circuit separately before deciding that the valve is the culprit.
- 02
Do you see moisture or dripping on the body of the gas valve, even though the rest of the installation is dry?
Cause: The internal seals of the gas valve have lost their sealing capacity over time.
Dry the area and turn on the boiler to identify the exact point of the leak before replacing the part.
- 03
The boiler takes a long time to switch service or resists doing so.
Cause: The switching mechanism is stuck due to dirt, limescale, or wear.
Bleed the circuit and check for any limescale residue in the area before replacing the gas valve.
Fault codes Saunier Duval that require diagnosis
| Code | Fault | Technical checks |
|---|---|---|
| F.20 | Safety shutdown: temperature limiter. | If the 3-way valve (priority valve) is blocked or disconnected, the primary flow does not switch correctly and the generator overheats, triggering the F.20; to verify, force the test/diagnosis that moves the valve from the service menu and check the power supply/wiring and ensure the shaft/motor are not seized. |
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 3-way valve S1025500.
- Catalogue reference
- S1025500
- Uniclima internal SKU
- V3VTC30E
- Brand
- Saunier Duval
- Type of part
- 3-way valves
- Units in stock
- 3 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.
- material
- PA66
Frequently asked questions about the 3-way valve S1025500
What is the reference for the Saunier Duval 3-way valve that I need to order?
For which ranges of Saunier Duval boilers is this 3-way valve compatible?
How many boiler models are compatible with this gas valve?
What symptoms indicate that I should replace this gas valve in my boiler?
What fault code is documented for this gas valve?
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