BoilerFaultCodesTechnical description
The boiler carries out a control stop at a flow temp of 80°C (modulation point + 5°C)
What causes this fault?
This fault occurs when the water temperature inside the boiler climbs too quickly, causing the system to pause to prevent overheating. The most common reasons are a slight restriction in water flow, such as trapped air or a build-up of sludge, or the circulation pump beginning to tire. It essentially means the heat cannot be moved away from the boiler into your radiators fast enough.
This code often appears during the first cold spell of autumn when the heating is turned on after a long summer break, as pumps can become slightly stiff or stuck.
DIY fix possible
Check that all radiator valves are open to ensure water can flow freely.Inspect the system pressure gauge and top up to 1.5 bar if it is low.Wait for the boiler to cool down, as it should restart automatically once the temperature drops.