The vent pipe should not go straight up , it elbows off the top of the cylinder to a tee , top of tee is the vent , bottom is HW draw off , basic stuff this mate .
Put a manufacturers shower pump connection on the top of the cylinder if you alter it .
If its an exact part swap with no pipework needed to be altered I will be honest it does sound enough
Obviously depends on the part then vat etc , if the valve isnt above the cylinder it is a bigger job .
Bloody hell pal , your poor mum . Continue what you are doing you cant do anymore, hopefully the vaccine may help her mentally . Sorry I couldn’t press the “like” button on a post like this .
Yes a big difference since Christmas / new year , phone very quiet here .
Hang on in there , work will come back with a vengeance when this is all over .
Problem is when ??