I have noticed a damp patch on the wall in the hallway downstairs, it
has been getting gradually larger over the last few days. I suspect
it is coming from the hot water cylinder which is located directly
above this wall. I have had a quick look and cannot see that it is
leaking from any of the nearby pipes so I suspect the leak may be from
the tank itself. Is replacing the cylinder something that can be
DIY'd without too much trouble ? Any advice or pointers which might
help ? It is an indirect system with the cold water tank directly
above in the loft.

While I may be forced into replacing the hot water cylinder, it gives
me the opportunity to bring forward one of those jobs which I have
been considering. That is to move the cylinder up into the loft. I
realise I will have to replace the HW cylinder and CW tank with a
combination unit but are there any drawback to this that I need to
consider ?