BoilerFaultCodesTechnical description
LON user number, adjustable from 1 to 99: 1-4=boiler, 5=cascade, 10-...=Vitotronic 050, 99=Vitocom
What causes this fault?
This fault occurs when two or more components on the boiler's internal communication network are trying to use the same identification number. It is usually caused by a technician incorrectly configuring the settings during a repair or by a digital glitch that has scrambled the control unit's memory. Because the system cannot distinguish between the different parts, it struggles to send and receive commands correctly.
DIY fix possible
Locate the power switch for your boiler and any external heating controllers.Turn the power off at the fused spur for 30 seconds, then turn it back on to restart the communication network.Check that any internet-connected modules or smart thermostats (like Vitocom) have a stable power supply and connection.