when i run the hot water tap on my viessmann vitodens 100 boiler it goes hot cold hot cold i have changed the ignition tranformer but its still doing it you can hear it ignite then go off then on again any suggestions
when the tap is running the temp went to 99 it read comfort underneath then the reset button started flashing and f2 came up on the lcdWhat temperatures does it show on the LCD? If you are seeing temperatures of 80C or more, your boiler probably needs a powerflush, due to clag from the heating system.
Which version is it - WB1A or WB1B?
When was it installed? It may be in warranty. If so, call Customer Service.
If it is leaking heat into the central heating during a hot water draw off, then your diverter valve is sticking. These problems are all caused by a system which is dirty, and therefore needs a powerflush. Just changing the plate heat exchanger is a waste of time and money.
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