BoilerFaultCodesThe 6 most common faults
Your boiler has stopped working because the amount of water in your central heating system is too low.
Locate the filling loop (a silver flexi-hose) beneath the boiler.Open the small valve or tap attached to the loop until you hear water flowing.Watch the pressure gauge on the front of the boiler until the needle reaches 1.5 bar (green zone).Close the valve tightly and check that the boiler restarts.
Your boiler has stopped working because the water pressure in the central heating system has dropped too low.
Locate the filling loop (usually a silver flexible hose) underneath the boiler.Open the one or two small valves on the hose until you hear water flowing.Watch the pressure gauge and close the valves once the needle reaches between 1 and 1.5 bar.
Your boiler has detected that the water pressure is too low for the system to operate safely.
Check the pressure gauge on the front of the boiler; it should be between 1 and 1.5 bar.Locate the filling loop (usually a silver flexible hose) under the boiler.Slowly open the valves until you hear water entering and the gauge rises to 1.5 bar, then close them tightly.
Your boiler has detected that the water leaving the unit is getting too hot, causing it to shut down for safety.
Check that all radiator valves are fully openEnsure the boiler pressure is between 1.0 and 1.5 barRestart the boiler using the reset button
Your boiler has detected that the water returning from your radiators is getting too hot, usually because the water isn't circulating properly through the system.
Check that at least two or three radiators have their valves turned fully openEnsure your central heating pump is running and not stuckTry resetting the boiler to see if the fault clears
Your boiler has detected that water is not circulating through the system correctly, causing a heat imbalance that has prompted the unit to shut down for safety.
Check that all radiator valves are fully openEnsure the boiler pressure is between 1.0 and 1.5 barCheck for any frozen external condensate pipes if it is winterReset the boiler using the control knob
on the Alpha CD24
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