I have been asked to replace an immersion heater on hot water storage cylinder that is not insulated , the system is open vented bye single pipe. When I went to look at it there was no information on the stat to tell me what length I need to buy , is there low relationship between the high of the cylinder and length of thermostat. I have never been asked to do this before as normally we take these systems out to put a new system in . Will be greatful for any information you can give
Thank you
Thank you