Saunier Duval STY 300 Safety Limit Thermostat
When you turn on the tap or start the heating, the Saunier Duval STY 300 Safety Limit Thermostat (reference S1047000) ensures that the temperature remains at safe levels. This part measures and controls the temperature of the circuit, preventing overheating. If it fails, you will notice incorrect readings, which can cause the boiler to lock out due to a false lack of pressure or not regulate the temperature properly. It is compatible with the Saunier Duval STY 300 boiler, among others. It should be replaced when it shows faults in readings or temperature regulation.
VAT included
Consult via WhatsAppCompatible Saunier Duval boilers
Manometer. A proven compatibility: Duval STY 300.
Proven compatibility
| Boiler model | Family | Verification |
|---|---|---|
| Saunier Duval STY 300 | Saunier | 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 it 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 —. If it is not visible, do not identify the part by 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 manometer resolves
The manometer shows the pressure of the boiler circuit. These are the typical symptoms and what to do:
Common symptoms and faults
- 01
The boiler suddenly cuts off the hot water for no apparent reason.
Cause: The limit thermostat has detected a temperature above the safety limit and cuts off the supply to protect the equipment.
Measure the actual water temperature with a thermometer: if it is very high, the cut-off may be correct and the fault may lie in the control thermostat, not in the limiter.
- 02
The reset has been triggered and it does not work again even when the button is pressed.
Cause: The safety limiter does not reset because it continues to detect high temperature or because the internal contact has been damaged.
Let the unit cool down properly before resetting: if it trips again immediately, there is a real thermal cause behind it and not just the thermostat.
- 03
The water comes out intermittently, sometimes hot and other times it suddenly stops.
Cause: A limiter that acts erratically can open and close the contact without there actually being an overtemperature.
Check that the normal regulation thermostat is not set too high, forcing the limiter to intervene.
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.
Saunier Duval pressure gauge datasheet
- Brand
- Saunier Duval
- Type of part
- Pressure gauges - Aquastats
- Units in stock
- 5 units
- Status
- Refurbished
- Warranty
- 1 year
- Shipping
- 1-2 business days
- 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.
- Regulatory marking
- CE
Frequently asked questions about the pressure gauge
What is the function of the limit thermostat in the STY 300?
Is this thermostat compatible with any Saunier Duval STY 300?
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