BoilerFaultCodesThe 6 most common faults
Your boiler is making a loud noise because the water pressure inside the system is too low for it to run properly.
Locate the filling loop (the flexible silver hose usually underneath the boiler).Slowly open the valve(s) until you hear water entering the system.Watch the pressure gauge and close the valves when it reaches 1.5 bar.
Your boiler has stopped working because there isn't enough water moving through the system to safely light the burner.
Check the pressure gauge on the front of the boiler; it should be between 1 and 1.5 bar.If the pressure is too low, use the filling loop valves to top up the water level.Ensure all radiator valves and isolation valves under the boiler are fully open.
Your boiler has shut down because it cannot detect any water or sufficient pressure to safely light the burner.
Check the pressure gauge on the front of the boiler; it should be between 1.0 and 1.5 bar.Locate the filling loop (usually a silver flexible hose) under the boiler.Slowly open the valve(s) to top up the pressure until it reaches 1.2 bar, then close them tightly.Reset the boiler to see if the fault clears.
Your boiler has built up too much water pressure, causing it to leak water from the safety pipe to protect the system.
Check that the filling loop valves are fully closed and not letting in water.Bled water from a radiator through the air vent to reduce system pressure.Monitor the pressure gauge to ensure it stays between 1.0 and 1.5 bar when cold.If the pressure continues to rise on its own, call a Gas Safe engineer.
Your boiler is struggling to push water through the pipes quickly enough, causing it to switch on and off repeatedly to avoid overheating.
Check that all radiator valves are fully openInspect the boiler pressure gauge and top up to 1.5 bar if it is lowCheck for any visible leaks around radiators or pipework
Your boiler has lost water pressure, which prevents it from heating up or providing hot water.
Check for any visible leaks around radiators or pipesLocate the filling loop (usually two braided hoses) under the boilerOpen the valves slowly until the pressure gauge is between 1.0 and 1.5 barClose the valves tightly and restart the boiler
on the Chaffoteaux Celtic 24 HE
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 Chaffoteaux 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