3-Way Valve for Isofast Condens F 35 E Boiler - Ref. S1025500
The 3-way valve for the Isofast Condens F 35 E boiler, reference S1025500 from Saunier Duval, is a component responsible for directing water between the heating circuit and the domestic hot water circuit. When this valve fails, you will notice that there is hot water but no heating, or vice versa, or even that both circuits are mixing. This part is compatible with models from the Isofast, Isomax, Isotwin, and Themafast ranges, among others. It is advisable to replace it if you experience these water distribution issues.
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
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
Hot water takes longer to come out when the tap is opened.
Cause: The three-way valve has a delay due to actuator wear.
Time the waiting period several times; if it is always the same length, the fault lies with the gas valve.
- 02
The heating stops working when a hot water tap is opened.
Cause: The valve prioritizes hot water and does not return to heating when the tap is closed.
Turn off the tap and wait a minute before checking if the heating starts working again.
- 03
An error code related to flow or switching appears frequently.
Cause: The gas valve sensor does not properly detect the circuit change.
Note the exact code displayed on the screen before purchasing; not all flow faults are due to the gas valve.
- 04
There is water accumulation or moisture at the base of the boiler without any visible leak.
Cause: The plastic body of the gas valve has cracked and is leaking through micro-fissures.
Dry the area, keep the boiler running, and locate the exact point of moisture before replacing the gas valve.
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
- 0 units
- Status
- Refurbished
- Warranty
- 1 year
- Shipping
- 1-2 business days
- Return
- 14 days
Frequently asked questions about the 3-way valve S1025500
Is this 3-way valve suitable for the Isofast Condens F 35 E?
Does the valve of the Isofast Condens F 35 E also work for other boilers?
How many models are compatible with this gas valve?
What fault code is documented for this gas valve?
Is S1025500 the reference marked on the part?
Spare parts related to Saunier Duval Isofast
