Baxi 225496BAX Thermocouple Sit 0.290.166

The Baxi 225496BAX is a thermocouple supplied for Baxi Solo floor-standing boiler models. It carries the SIT 0.290.166 thermocouple reference and is fitted at the pilot assembly, where the pilot flame heats its tip and the device generates a small current. That current holds the gas valve open, allowing the burner to run once the pilot has proved.

Because it is a flame-sensing safety component, the thermocouple is the part that decides whether the boiler is allowed to stay lit. A weak or failed thermocouple will not hold the valve in, and the pilot will drop out.

• The pilot lights, but goes out as soon as the gas valve button is released
• The gas valve has to be held down for 10 to 20 seconds and the pilot still will not stay lit
• The pilot extinguishes repeatedly no matter how long the valve is depressed
• Voltage measured across the thermocouple, with it disconnected from the gas valve, reads below the expected level
• The pilot flame is stable and correctly positioned, yet the boiler will not hold on pilot

• Check the appliance data badge for the exact Solo model and confirm the thermocouple fitted is marked SIT 0.290.166
• Have the boiler GC number and serial number to hand when checking compatibility
• This part is fitted to a gas appliance; installation must be carried out by a Gas Safe registered engineer.