Why don’t you get the engineer that service’s it to take a look at it before buying parts you probably won’t need.
If as I suspect you haven’t had...
We cut them tight to the wall using a 9ins grinder with a metal disc and a vacuum cleaner helps to keep the dust down.
Then fit a cast iron to...
Have you checked the shower hose is not twisted and the filters and non return valves in the shower valve are ok if fitted.
Clockwise is off anti clockwise is on
Did you fit the new hot water seal in the back of the shower
NO you can not make any modifications to an unvented cylinder unless it's approved by the manufacturer
The answer is NO
DrWho the wind up merchant
That's a common fault easily repaired you don't need a new boiler
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