I have a cylinder that provides the hot water for our flat. Recently, we noticed that the overflow was dripping o some work on the ballcock is required but on looking at the cyclinder I am unsure if we dont also have an additional problem as physically it looks as though there is a slight leak. To keep things simple and safe I would like to remove the cylinder and replace it but I am struggling to "identify" the type of cyylinder I have. This may seem strnage but the cylinder appears to be in two parts. THe main unit appears prety standard and contains two seperate heater elements. Interestingly though, there is what I think is some sort of "header" tank that sits on top of the main cylinder and contains cold water as well as the ballcock and the overflow. This tank is also open to the elements. The water in this tank is never anything but cold, it is fed directly from the mains. THe cold water suply as one would expect is direct from the rising main and both the cold supply in bathroom and kitchen are fed from the main, not via a tank as best as I can tell.
My question(s) firstly, what type of cylinder do I have and are replacement cylinder easily found? (The property is approximately 15 years old). Is the "extra" tank a header tank as I assume and is it only feeding the cylinder beneath? Is this really some form of gravity fed system or is the main cylinder sealed and the hot water supply is under pressure (the hot water supply presure is poor at the best of times but all propertiues in the development seem to have this issue??)
THanks for any help!
Jasper