Not sure if this is a plumbing or a sparks question, but here goes: I have a 30 year old back boiler type heating system in a bungalow: Parkray Everglow gravity anthracite heats 9 radiators and an indirect hot water cylinder. System is vented to an expansion tank. The domestic hot water cylinder can boil back into main tank in the roof. In the summer the hot water is heated via a long immersion inserted via a boss in the top of the copper cylinder. The immersion lasts 5 - 10 years before splitting and thus triggering the circuit breaker. Last summer I had to replace the immersion for the 4th or 5th time. This is a bggr of a job, cos the boss is at the back of the tank, there are pipes in the way and too little headroom. I have to resort to using a mirror to see what I'm trying to do with the wiring. This spring I was well pleased when the 9 month old immersion failed to work. Figured it must be the thermostat that had "failed" after such a short period. Struggled to extract the thermostat and eventually realised that there is a darning needle sized hole marked "reset" in minute letters. Some time during the winter the anthracite had managed to heat the hot water hot enough for the "new" belt and braces safety system in the immersion to lock off the electrical supply. Guess what - I've refitted the thermostat from last summer's old scrap immersion, so problem solved for the immediate future. Would I be right in thinking that some civil servant got an attack of the vapours thinking about the number of unvented systems these days and so all immersions now have to be fitted with a thermal cut out ? Or can I still get my hands on a thermostat without the overheating cut out. I really cannot see the missus climbing into the airing cupboard with a darning needle, a mirror and a small spanner to remove the cover and then managing to "reset" the immersion's thermostat. Harry. PS Any one got a second hand Parkray Everglow, mine is on its last legs but I don't fancy "upgrading" to oil at 700 GBP per tonne. Might be able to make one good out of two old ones?