Unvented cylinder advice needed.?
The electronic unit works a bit like a sacrificial anode,because the cylinder is unvented is irrelevant.It’s more to do with the material that its made from. The fact that the cylinder has been sitting cold will mean that the lime scale might not be that much of an issue as the deposits are only released when the water is heated.The cylinder might well be corroded but then again you might be lucky.Drain the cylinder down and look for specs of rust in the water.Flush it through,refill it then heat the water. No one knows how badly damaged the tank will be until it’s re commissioned.Use a G3 registered plumber to test it and advise you further.
