Viessmann boiler failure

[Mark Hennessy]

There was a tragic case a few years back where a faulty electric immersion heater stuck on. Eventually the water in the plastic header tank in the loft became heated, the tank failed, and scolding hot water came cascading through the ceiling.

When searching for a link, I came across many similar cases of death and serious injury. This is the one I had in mind: http://news.bbc.co.uk/1/hi/england/somerset/7175037.stm

New immersion heaters have 2 thermostats in series.