3-Way Valve Motor Saunier Duval Isofast F 30 E H MOD Ref. S1025500
The 3-way valve switches the water between the heating circuit and the domestic hot water circuit. If it fails, you will notice that there is hot water but no heating, or vice versa, or there may even be a mix of both circuits. This valve is compatible with several boiler models, such as those in the Isofast range, including the F 30 E H-MOD and the F 35 E H-MOD, among others. The manufacturer's reference is S1025500. It should be replaced when there are issues with heating or hot water, or if the fault code F.20 appears, which indicates a safety disconnection due to a temperature limiter.
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
The boiler is working, but the gas valve motor keeps trying to turn.
Cause: The motor cannot find the limit because the internal gear is worn or broken, and it keeps trying to position itself.
Listen for a few seconds after turning on the boiler: if the motor does not stop, it is more likely that the fault is with the motor.
- 02
The valve motor makes no noise and does not move when requesting heating or domestic hot water.
Cause: The motor winding has burned out or lost power and cannot move the shaft.
Measure with a multimeter if power is reaching the motor connector when the boiler requests service; if power is present and it does not move, the motor is faulty.
- 03
It smells like burnt plastic near the gas valve when the boiler has been running for a while.
Cause: A forced motor against a seized shaft overheats and can melt part of its plastic casing.
Turn off the boiler and locate the source of the smell before continuing to use it; if it comes from the gas valve motor, do not force it any further and disconnect it until it has been checked.
- 04
The boiler operates erratically, alternating between heating and domestic hot water without intervention.
Cause: The motor loses the reference position and the control unit continuously retries the switching cycle.
Note if the erratic change coincides with power outages; if not, it is more likely that the problem is with the valve motor.
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.
- number
- 5?18?00
- serial number
- 2?005 / 1?0
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.
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