Alpha E25 Fault

Alpha E25 Fault

The Alpha E25 error code indicates a “Dry Fire” condition. This fault occurs when the boiler attempts to operate without detecting the presence of water in the system, or when there’s insufficient water flow to carry out the heating process safely. It’s a protective measure to prevent damage to the boiler’s components from overheating due to the lack of water.

Causes of Alpha E25 Error Code

  1. Low Water Pressure: If the water pressure in the system drops too low, it might not be sufficient to circulate through the boiler, triggering the E25 error.
  2. Faulty Flow Sensor: A malfunctioning flow sensor may fail to detect water in the system even when there is adequate pressure, leading to a dry fire warning.
  3. Blocked Heat Exchanger: A blocked or heavily scaled heat exchanger can restrict water flow, simulating a dry fire condition.
  4. Airlocks in the System: Air trapped within the heating system can impede water flow, potentially causing the boiler to detect a dry fire scenario.

Troubleshooting and Resolving the Alpha E25 Error Code

  1. Check Water Pressure: Inspect the boiler’s pressure gauge to ensure the pressure is within the recommended range (usually between 1 and 1.5 bar). If it’s too low, repressurize the system according to the manufacturer’s instructions.
  2. Inspect and Clean the Flow Sensor: The flow sensor should be checked for any signs of malfunction or debris. Cleaning or replacing a faulty flow sensor should be done by a professional.
  3. Flush the Heat Exchanger: If the heat exchanger is blocked or scaled, it may need flushing or chemical treatment to restore proper water flow. This task is best performed by a qualified heating engineer.
  4. Bleed Radiators to Remove Airlocks: Air trapped in the system can be removed by bleeding the radiators, which might resolve the issue if airlocks are causing reduced water flow.
  5. Reset the Boiler: After addressing potential causes, reset the boiler to clear the error code and attempt to restart. Consult the boiler manual for the correct reset procedure.
  6. Professional Assistance: Because diagnosing and repairing a dry fire condition involves several components of the heating system, it’s advisable to seek help from a Gas Safe registered engineer. A professional can accurately identify the root cause of the E25 error and carry out necessary repairs or adjustments safely.


The Alpha E25 error code is a serious warning that the boiler is operating or attempting to operate without adequate water flow, posing a risk of damage to the boiler and potentially unsafe conditions. Addressing this error involves checking water pressure, inspecting key components like the flow sensor and heat exchanger, and possibly seeking professional assistance to ensure the system operates safely and efficiently. Regular maintenance can help prevent such issues by ensuring the heating system is in good working order.