BoilerFaultCodesTechnical description
The boiler is waiting in response to a heat demand – the boiler regularly switches to partial load
What causes this fault?
This code occurs when the water inside the boiler heats up much faster than it can be circulated around your home. It usually happens because the pump is struggling to move water or your radiators are turned off, causing heat to back up inside the unit. To prevent overheating, the boiler automatically throttles back its power until the temperature stabilizes.
This is more common in spring and autumn when thermostatic radiator valves are frequently closing as the house reaches temperature, restricting the flow of water.
DIY fix possible
Ensure at least two or three radiators have their valves fully openCheck that your thermostatic radiator valves (TRVs) are not all set to 'zero' or 'off'Verify that the central heating pump is running and not stuck