Here's the deal: If your Vitodens 100 has outdoor temperature sensing capability, either built in or via external aftermarket control such as Tekmar or other, and the temperature outside is above warm weather shut down (WWSD), then the boiler will not operate for space heating, but will operate to make Domestic Hot Water (DHW) only. Generally speaking WWSD is facoty set at 20*C, since this is normal room temperature so the boiler will not need to operate at temperatures above this number as it is warm enough outdoors to heat the house to comfortable levels.
If your Vitodens 100 does not have outdoor temperature sensing capability then you should check to see if your room thermostats are operational and calling for heat since the boiler is only responding to this on-off control based on room temperature. (turn up your room thermostats)
In both cases you need to make sure that your heating system's distribution pump and zone valves are operating correctly.
In any case you should be calling a heating contractor if you suspect that there is a problem with your boiler and/or heating system.
Good luck.
New diverter valve
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Yep, mine is doing this too.
Sams issue. Got it going before the holiday and now although I have hot water, I have no heating.
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