BoilerFaultCodesThe 6 most common faults
Your boiler has stopped working because it failed to light the internal flame, resulting in no heating or hot water until it is successfully restarted.
Turn the selector dial on the front of the unit to the 'Reset' position.Wait for 30 seconds for the boiler to click and attempt the ignition sequence again.If the boiler fails to ignite repeatedly, check that your gas supply is turned on and your gas meter has credit.
Your boiler has tried to light several times but has been unable to successfully create a flame to start heating your water.
Check that your gas credit hasn't run out or that the emergency control valve is openPress and hold the Reset button for 2-3 seconds until the error clearsCheck if other gas appliances in your home, like a hob, are working correctly
Your boiler has switched itself off because moving water inside the system has become too hot.
Check that all radiator valves are fully openEnsure the system pressure is between 1.0 and 1.5 barPress and hold the reset button for several seconds
Your boiler has detected that the water pressure in the system is too low to operate safely, which has caused it to shut down temporarily.
Locate the filling loop (usually a silver flexible hose) underneath the boiler.Open the one or two small taps on the loop slowly until you hear water flowing.Watch the pressure gauge and close the taps firmly once it reaches 1.5 bar.
Your boiler has lost its connection with your external thermostat or remote control unit, preventing it from receiving heating instructions.
Check the batteries in your room thermostat and replace them if necessaryEnsure the wireless receiver is powered on and within range of the thermostatRestart the boiler using the reset button to see if the connection re-establishes
Your boiler's internal thermometer is sending incorrect or missing information, which has caused the system to stop working for safety.
Turn the boiler off at the main electrical switch.Wait for 30 seconds.Turn the power back on and press the 'Reset' button.
on the Alpha Cd25
Based on parts cited in our fault code database. Your engineer will confirm what's actually needed after diagnosis.
Call a Gas Safe engineer if…
- You can smell gas or see signs of a leak
- The Alpha shows an Emergency or High severity code
- The boiler keeps locking out after repeated resets
- You've tried the DIY checks and the fault hasn't cleared
- There's visible water leaking from the boiler
- The flame is yellow or orange instead of blue