Peter wrote in message


"My parents have had a couple of immersion 'stats fail, twice
resulting
in the supply flex burning and cutting off the supply. But once it had
managed to heat the cold tank upstairs till it was quite warm. At the
time I had suggested a second external tank 'stat..."

Maybe an upgrade to the new thermostat, with the cut-out device would
be a sound idea for many existing immersion heaters. It shouldn't
involve draining and removing the immersion heater. About £4.13 plus
Vat & delivery from BES.ltd.uk (for example) , Part No. 1665.

Their blurb says; "Universal type, conform to the new standard EN
60335.2.73, for use within all heaters. Can be fitted into 'old type'
heaters to upgrade to the latest standard. 16 A 240 V thermostat. BEAB
approved."