Bulb and Capillary Aquastat Saunier Duval SD 235 C / Thelia 623 - Ref. 52914
When you open the tap or turn on the heating, the Saunier Duval SD 235 C / Thelia 623 bulb and capillary aquastat - Ref. 52914 is responsible for measuring and controlling the pressure or temperature of the circuit. If this part 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. This aquastat is compatible with models such as the SD 235 C, Thelia 623, among others in the Saunier Duval and Thelia range. It is recommended to replace it when you start to observe those symptoms of malfunction.
VAT included
Consult via WhatsAppCompatible Saunier Duval boilers
Manometer. Five confirmed compatibilities: 235 C and 623.
Proven compatibility
| Boiler model | Family | Verification |
|---|---|---|
| Saunier Duval 235 C | SD | Contrasted |
| Saunier Duval 623 | THELIA | Contrasted |
| Saunier Duval 123 | THEMIS | Contrasted |
| Saunier Duval 223 | THEMIS | Contrasted |
| Saunier Duval 23 | THEMIS | 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 heating does not heat enough even when you set the control to maximum.
Cause: The capillary bulb is not making good contact with the water and sends a higher temperature reading than the actual one, cutting off prematurely.
Check that the bulb is properly fitted in its sleeve and submerged in the water circuit.
- 02
The safety cut-off of the boiler is triggered without you noticing the water is particularly hot.
Cause: A stuck internal contact or a damaged capillary causes the system to interpret that the temperature limit has been exceeded.
Check for kinks, crushes, or liquid leaks along the capillary.
- 03
The boiler does not respond to the heating demand: neither the pump nor the burner starts.
Cause: If the aquastat contact remains open, the control board does not receive the signal to turn on.
With the boiler cold, check with a multimeter that there is continuity between the terminals of the aquastat.
- 04
The behavior is intermittent: it heats for a while, stops, and then starts again for no clear reason.
Cause: A contact with poor mechanical support or some oxidation causes switching that does not depend on the actual water temperature.
Before changing the aquastat, check that the connector and the wiring terminals are properly tightened.
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
- 1 unit
- Status
- Refurbished
- Warranty
- 1 year
- Shipping
- 1-2 business days
- Return
- 14 days
Frequently asked questions about the pressure gauge
Does this aquastat with reference 52914 work for the Saunier Duval SD 235 C?
Is it the same part that the Saunier Duval Thelia 623 uses?
How do I identify this aquastat in my boiler?
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