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 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 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
Your boiler is gaining too much water pressure, which could eventually cause it to leak or shut down for safety.
Check that the external filling loop valves are tightly closedDisconnect the silver braid filling loop hose if it is safe and possible to do soBleed a radiator to reduce the system pressure back to 1.5 barMonitor the gauge; if pressure continues to rise with the loop disconnected, call an engineer
Your boiler is making a loud noise because the internal pump that moves water around has stopped working.
Full guide for 2bYour boiler is struggling to heat your water at the correct temperature because an internal component responsible for controlling air flow is the wrong type for this specific model.
Full guide for 5.ivon 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