This Safety Alert (SA) has been published to provide guidance to Gas Safe Registered businesses/engineers about a product safety concern relating to seven Viessmann Vitodens 100 – W system boilers.


Gas Safe Register has been advised by the manufacturer of a risk resulting from a potential faulty seal in the gas valve affecting seven boilers known to be in the UK.

Viessmann Ltd has identified a very limited batch of Vitodens 100-W system boilers that may have a potential issue with the gas valve. Only seven boilers are affected. It has been identified that over time, there is a potential for the seal to deteriorate and for gas to leak through the gas valve. This is a supplier issue that has been contained, with the exception of a small number of boilers that have entered UK distribution channels and which Viessmann has been unable to trace. If the boilers have been installed, the installations will have taken place in 2016.

Affected models
Only the following seven Viessmann Vitodens 100-W serial numbers are affected:

7543420601446103System 19kW Boiler
7543421601692101System 26kW Boiler
7543421601693108System 26kW Boiler
7543421601715107System 26kW Boiler
7543421601716104System 26kW Boiler
7543421601719105System 26kW Boiler
7543421601727100System 26kW Boiler
All these serial numbers relate to Viessmann Vitodens 100-W system boilers only.

How to identify the boilers affected
Serial number can be found in one of the two following locations on the boiler case:

What do I need to do if I own, use or service one of these boilers?
If the boiler has been installed contact Viessmann who will make arrangements to replace the gas valve, or if the boiler has not been installed, contact Viessmann to have the complete boiler replaced. Any customers, gas users or registered businesses who have concerns with regards to their Viessmann Vitodens 100-W boiler should contact Viessmann Ltd.
For further information please contact Viessmann:
Tel: 01952 675060


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