BoilerFaultCodesThe 6 most common faults
Your boiler has switched itself off because it has reached an unsafe temperature and needs to cool down before it can run again.
Turn off the boiler and allow it to cool for 20 minutes.Ensure all radiator valves are fully open to allow water to circulate.Press the Reset button on the front control panel to restart the system.
Your boiler is failing to light the gas burner, which means it cannot provide heat or hot water.
Check if other gas appliances in your home, like a hob, are working to confirm your gas supply is on.Ensure your gas meter has credit if you use a prepay meter.Press the 'Reset' button on the front control panel and wait for the boiler to restart.
Your boiler has stopped working because water is not moving around the internal system properly, causing it to shut down to prevent overheating.
Check that the boiler pressure gauge is between 1 and 1.5 barEnsure all radiator valves and isolation valves under the boiler are fully openGently bleed your radiators to remove any trapped air pocketsReset the boiler using the 'R' or Reset button
Your boiler has detected that there is not enough water pressure in the system to operate safely.
Locate the filling loop (usually a silver braided hose with small valves underneath the boiler).Open the valves slowly until you hear water flowing and the pressure gauge reaches between 1.0 and 1.5 bar.Close the valves tightly and restart the boiler.
Your boiler has shut down because it is missing its basic supply of gas, water, or electricity.
Check if your gas supply is turned on and other gas appliances are working.Ensure the boiler is plugged in and the fused spur switch is in the 'on' position.Check your property's consumer unit (fuse box) to see if a circuit breaker has tripped.Verify that the water pressure gauge is between 1 and 1.5 bar; top up if necessary.
Your boiler's internal thermometer for the heating system has stopped working, meaning the unit cannot safely tell how hot the water is and has shut down as a precaution.
Full guide for 12on the Chaffoteaux Calydra 23 Green
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