Anyone can help me please with our Santon Premier Plus unvented water system?

Hi Bad news. YOU MUST NEVER work on an unvented hot water system unless you are qualified and competent. Go to youtube and look for unvented cylinder disasters and you will see why this is the case. Good news is that a great many plumbers are certified to work on these systems, but seriously - don't let anyone who is not qualified and competent work on your system, it's likely to cost you in the long run. Sorry to be such a downer, it's just so dangerous. Did you know that when water turns to steam it expands by volume 1,600 times. Unvented systems are protected against this happening but must be properly cared for. Nige

What is the problem, James

hi,this is not safe if one off the overheat stats are faulty,you will cook the tank, and maybe allready done so with one of the pipes leaking ,i would get some one out asap,if the sencer pocket is leaking it may need a new tank as well if it has rotted,phil

it sounds as if you are describing the emersion heaters for the cylinder although there are thermal controls inside the emersion heater housings. you probably have a thermal control failure maybe caused by the water leak you have described. Get an engineer familiar with this type of system to sort it out it really needs to be done properly.