BoilerFaultCodesThe 6 most common faults
Your boiler has detected that the water pressure in the system is too low to run safely and has shut down as a precaution.
Locate the metal braided filling loop underneath or near the boiler.Slowly open the small handles on the valves until you hear water entering the system.Watch the pressure gauge and close the valves once the needle reaches between 1.0 and 1.5 bar.
Your boiler has stopped working because it has detected that the water inside it is getting too hot.
Check that all radiator valves are open to ensure water can circulate.Ensure there is enough water pressure by checking the gauge is between 1 and 1.5 bar.Press the 'Reset' button on the front of the boiler.
Your boiler has lit correctly but is struggling to keep the flame burning, causing it to shut down for safety.
Check that your gas emergency control valve is fully openIf you have a prepayment meter, check that you have sufficient creditTry resetting the boiler by pressing the 'Restart' button
Your boiler is failing to keep a flame lit, which means the system has shut itself down for safety and you will not have any heating or hot water.
Check if other gas appliances in your home (like a hob) are working to ensure gas is reaching the property.Ensure your gas meter has credit if you have a prepaid meter.Check if the white plastic condensate pipe leading outside has frozen during cold weather and thaw it with warm water.Press the 'Reset' button on the front of the boiler for five seconds.
Your boiler is overheating because water is not flowing through your heating system properly to carry the heat away.
Check all your radiator valves are turned fully open and not stuck shut.Ensure your central heating system pressure is at the correct level (typically 1.0–1.5 bar on the gauge).Check under the boiler to ensure the red isolation valves on the pipework are turned into the open position.
Your boiler has stopped working because the electrical supply from the grid or your home's wiring has dropped below the level required for the unit to run safely.
Full guide for F7on the Keston System S30
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 Keston 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
Avoid the next call-out bill
Monthly cover means no unexpected bills when your boiler breaks down.
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