Gas Valve Thema Condens 25-A
The gas valve Thema Condens 25-A regulates and allows the flow of gas to the burner according to the commands from the boiler's PCB. When it malfunctions, the boiler may fail to ignite, experience flame lockouts, or have modulation issues. Symptoms that may appear include faults such as F.26, F.27, F.28, F.56, and F.61. This model is compatible with the boilers Thema Condens 25 A and Themafast Condens 25 A, among others. It is recommended to replace it if the mentioned symptoms occur or if the associated fault codes are detected.
VAT included
Consult via WhatsAppSaunier Duval boilers compatible with reference 0020084503
Gas valve with reference 0020084503. Two confirmed compatibilities: Thema Condens 25 A and Themafast Condens 25 A.
Proven compatibility
| Boiler model | Family | Verification |
|---|---|---|
| Saunier Duval Thema Condens 25 A | Thema Condens | Contrasted |
| Saunier Duval Themafast Condens 25 A | Themafast Condens | 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 the reference 0020084503 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 0020084503. 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 gas valve 0020084503 resolves.
The gas valve regulates and modulates the gas flow to the burner. These are the typical symptoms and what to do:
Common symptoms and faults
- 01
The boiler tries to ignite, goes through the cycle, but does not manage to light the flame.
Cause: If the gas valve does not open the gas flow or does not do so in time, the control board does not detect a flame and blocks the ignition for safety.
Check that gas is reaching the boiler's inlet and that the main shut-off valve is open before replacing the gas valve.
- 02
The flame appears unstable, changing color or size for no apparent reason.
Cause: The valve regulates the gas flow through a modulating coil, and if it does not dose properly, the flame becomes irregular.
Check the condition of the burner and the cleaning of the injectors before replacing the gas valve.
- 03
The boiler loses modulation: it always operates at full power or gets stuck at a certain power level.
Cause: The modulating coil of the valve loses accuracy with use and stops adjusting the flow to the actual demand.
Measure, if you have a multimeter, that the signal sent by the PCB to the gas valve varies and does not remain fixed.
- 04
You notice a gas smell near the boiler when turning it on or off.
Cause: It may indicate a leak in the valve itself or in its sealing joints.
Shut off the gas, ventilate the area, and do not reset the boiler: notify a technician before considering changing any parts.
- 05
The boiler ignites well when cold but does not reduce the flame when the heating demand decreases.
Cause: The gas valve is not cutting off the gas flow even though the PCB is requesting it.
First, rule out that the temperature sensor is not giving an incorrect reading before touching the gas valve.
Fault codes from Saunier Duval that this spare part resolves.
| Code | Fault | Diagnosis and solution |
|---|---|---|
| F.26 | Fault: gas valve not functioning. | The stepper motor/drive of the gas valve is not operating or is disconnected/faulty, so the valve mechanism does not open/close; check continuity of coils, connector, and harness to the PCB and perform output test. |
| F.27 | Safety shutdown: incorrect flame detection. | Non-sealed gas solenoid valve/valve assembly that allows gas to pass when it should be closed, causing a false flame signal; check the valve's seal/closure and ensure the flame extinguishes immediately when demand is cut. |
| F.28 | Start-up fault: ignition failed. | Incorrect or faulty gas valve prevents correct gas supply during ignition; check power supply to the valve during the sequence, adjust/check the condition of the gas assembly, and replace the gas valve if coils are open/blocked. |
| F.56 | Fault in the regulation of the circulating flow sensor. | Defective gas valve causes incorrect air-gas regulation (mentioned by the manufacturer) or fault in its wiring; check the harness towards the valve and the operation/modulation of the gas assembly. |
| F.61 | Gas valve control fault (activation error). | Short circuit/ground fault in the harness to the valve or damaged valve coils; check insulation to ground, coil resistance, and control power supply from the PCB. |
| F.62 | Gas valve fault. Disconnection delay. | Gas valve that closes with delay or is not sealing, maintaining flame signal after cutting gas; check shutdown time, tightness, and replace if closure is not immediate. |
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 gas valve Saunier Duval 0020084503
- Catalogue reference
- 0020084503
- Brand
- Saunier Duval
- Type of part
- Gas valves
- Units in stock
- 1 unit
- 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.
- Voltage
- V1+V2 24 Vac
- Current
- 0.42 A
- Maximum pressure
- 60 mbar
- Ambient temperature
- -15 to 70 °C
- Gas class
- CAT III, Class B+C
- CE code
- 0006493878
- The technical data (voltage, current, pressure, temperature, gas class) comes from the data plate, but it is not accompanied by brand or commercial model.
Manuals and technical documentation
Official documentation of the boiler, useful for locating the part and cross-referencing the fault codes.
- Saunier Duval Thema Condens 25 A Manual (PDF)Document © Saunier Duval, provided as a technical reference.
Frequently asked questions about the gas valve 0020084503
For which models is the gas valve Thema Condens 25-A (reference VGCTCF30X) compatible?
What voltage and current does the gas valve Thema Condens 25-A operate at?
What is the maximum allowable pressure of the gas valve Thema Condens 25-A?
What fault codes are documented for the gas valve Thema Condens 25-A?
What type of gas does the gas valve Thema Condens 25-A accept?
Spare parts related to Saunier Duval Thema Condens
