BoilerFaultCodesThe 6 most common faults
Your boiler has temporarily shut down because it got too hot inside, but you can usually fix this by simply resetting the system.
Check that your home's radiators are turned on and TRVs are not all closed, as this restricts water flow.Locate the selector switch on the front of your Alpha CD28 boiler.Rotate the selector switch to the reset position (position 3) and hold it briefly to clear the fault.
Your boiler has stopped working because the burner failed to start up safely.
Locate the selector switch on your boiler.Rotate the switch to the reset position and wait for about 30 seconds.Allow the ignition sequence to restart automatically.
Your boiler has temporarily stopped working because the water pressure inside the system has dropped too low.
Locate the filling loop under your boiler or near the hot water cylinder.Open the valves slowly to let water into the system until the pressure gauge reads between 1.0 and 1.5 bar.Close the valves firmly and check the boiler display or reset the unit if necessary.
Your boiler has detected an issue with its internal temperature measuring system, so it has temporarily stopped working to keep things safe.
Full guide for Neon B Flashing on and offYour boiler is struggling to circulate water properly, which usually means the water isn't flowing freely around the system.
Full guide for Neon A Illuminated continuously and B flashingYour boiler has detected an issue with safely removing exhaust gases outside, so it has locked itself out to prevent any risk.
Full guide for Neon A and B Flashing on and off at the same timeon the Alpha SY9 24
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