3-Way Valve Motor Saunier Duval Isofast C 35 EA Ref. S1025500
Three-way valve for Saunier Duval boilers from the Isofast/Isotwin/Themafast range indicated. The body is made of PA66 polyamide, according to the recycling symbol molded next to one of the ports. The manufacturer's name of the component is not engraved, nor is there an identifiable commercial reference code. It is replaced when it becomes stuck or loses tightness between heating and domestic hot water.
VAT included
Consult via WhatsAppSaunier 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
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 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 and faults that the S1025500 three-way valve resolves.
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
After the summer, the heating does not start even though the hot water from the tap works well.
Cause: The plastic body has been stationary in the same position for months, and the internal mechanism is seizing up.
Force several heating and domestic hot water cycles in succession before replacing it: sometimes it releases itself after the first use of autumn.
- 02
The tap water temperature changes suddenly, without any apparent reason.
Cause: The internal shutter does not fully close one passage and allows water to flow from both circuits at the same time.
Check if there is a thermostatic or mixing faucet nearby that could be causing the same symptom before inspecting the gas valve.
- 03
There is a water leak right at the plastic body of the valve, not at the connections.
Cause: The material of the body, over the years and heat cycles, can lose its tightness either in itself or in its internal joints.
Differentiate if the leak comes from the body or from a connection fitting, and tighten the latter before replacing the part.
Fault codes from Saunier Duval that this spare part resolves.
| Code | Fault | Diagnosis and solution |
|---|---|---|
| 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
- 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
Data read on the part and in the manufacturer's documentation
What we have not been able to verify does not appear here.
- Body material
- PA66 (polyamide 66), according to the recycling symbol molded on the part
- Additional marking
- Code 'UN20014407' molded on the body; due to its format, it is interpreted as a mold or batch marking, not as a commercial reference.
Manuals and technical documentation
Official documentation of the boiler, useful for locating the part and cross-referencing the fault codes.
- Saunier Duval F 35 E H-MOD Manual (PDF)Document © Saunier Duval, provided as a technical reference.
Frequently asked questions about the 3-way valve S1025500
What material is the 3-way valve of the Isofast C 35 E-A made of?
Is the code 'UN20014407' engraved on the valve the commercial reference?
When should the 3-way valve of a Themafast boiler be replaced?
Is this valve Ref. S1025500 suitable for a Eura 3 25 E boiler?
Spare parts related to Saunier Duval Isofast
