BoilerFaultCodesThe 6 most common faults
Your boiler's internal water pressure is currently too high, which prevents it from operating safely to protect the system.
Locate a radiator in your home with a bleed valvePlace a cloth and container under the valveOpen the bleed valve slowly to release water until the boiler pressure gauge drops to the green zone (usually 1.5 bar)Close the valve tightly
Your boiler has temporarily stopped heating because the water is not flowing through the system correctly, likely due to low water pressure or an airlock.
Check your boiler pressure gauge to see if it is below 1 bar.If low, use the external filling loop or internal key to top up the boiler pressure to 1.5 bar.Bleed your radiators to release any trapped air and then re-check the pressure.
Your boiler has stopped working because the water pressure inside the heating system has dropped too low.
Locate the filling loop (a silver flexible hose) underneath the boiler.Open the small valve or tap on the loop to allow mains water into the boiler.Monitor the pressure gauge on the front until it reaches 1.5 bar, then turn the valve firmly off.
Your boiler is struggling to move water around the system fast enough, likely due to low water pressure or a blockage.
Check your boiler pressure gauge; if it is below 1 bar, use the filling loop to top it up to 1.5 barEnsure all radiator valves are fully openTurn the boiler off and back on again to reset the temporary fault
Your boiler has detected that there is not enough water pressure inside the system for it to heat your home safely.
Locate the external filling loop, which is usually a silver braided hose under the boiler.Open the valves attached to the loop slowly to allow water into the system.Monitor the pressure gauge on the front of the boiler until the needle reaches between 1.0 and 1.5 bar, then turn the valves off securely.
Your boiler is trying to start but the flame is not catching, meaning it cannot provide you with heating or hot water.
Full guide for F28on the Heatline Vizo 28
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 Heatline 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