BoilerFaultCodesTechnical description
Diverter valve by Viessmann
What causes this fault?
This fault occurs when the internal motor that moves the diverter valve fails to reach its intended position, often because the valve has become stuck or stiff. This is usually caused by a buildup of debris or sludge from the heating system water getting inside the moving parts, or eventually, the motor simply wearing out over time.
This issue is frequently noticed in autumn when homeowners switch their heating back on for the first time, putting strain on a valve that has remained stationary all summer.
Engineer required
This is a high severity fault. Stop using the boiler and call a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
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