If you only have an immersion heater, then the safety cut out is often not reset-able, but if you have a second way to heat DHW then it needs to be reset-able as it could for example trip due to solid fuel back boiler going over temperature and not down to a thermostat fault.
With a thermosetting plastic or a metal header tank, there is no real problem anyway, if the water does boil, you will hear it, and it will fill loft with steam, and maybe shoot water out of the overflow, but no real danger, however with thermal plastic header tanks there is a real danger
the
death of a baby in 2006 was big news, and it seems the wrong thermostats were being fitted, in the early days the cut out was not built into the thermostat
arrow is pointing to the cut out, and the thermostat designed to have a separate cut out was fitted instead of the one with the built in cut out
you can see the little reset hole in this one.
I hate statements like this
who recommends it? In most immersion heaters there is no provision to fit extra safety cut outs, and I know as a child the water would boil quite regularly, and mother would send me to run off some hot water, how anyone could ignore the noise it made I do not know, however the real problem is the use of thermal plastic for the header tanks. Should really be thermal setting type or "hard plastic" yes I know can't be plastic and hard, but you know what I mean.
