hot water tank emptying

hi,
i have a hot water tank which empties itself when i turn the temperture up to 50 degrees from 45degrees.this did not always be the case.i have changed the tank stat and the pressure vessel.any ideas what could be causing it would be greatly appreciated.tank stat used to be set at 70 degrees up until a couple of years ago when we have steadily been decreasing it to stop the blow off.flow regulator set at 0.2bar and mains pressure set at 1.5psi.

your cylinder needs a service, it also possibly needs a new temperature and pressure valve, get someone that understands unvented cylinders (G3 in ireland ?)

is the hot water tank not a sealed therefore how can it be serviced.i have changed the stat on the side of the tank already with no improvement.

tigertom said:

is the hot water tank not a sealed therefore how can it be serviced.

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good point you have there, what was I thinking, ignore what I wrote and keep changing parts, there arent that many so you should have it sorted pretty quick like.