Just completed a shower in an en-suite. Problem is that the hot flow is
very slow and makes the shower very feeble. I've had a look at a pump
but know very little about such things. Can someone answer the
following:-

The hot water flow for reasons of practicality had to come down to the
kitchen from the tank in the airing cupboard and then back up again to
the en-suite (hence feeble flow). The mains cold just goes straight up
to the shower and is quite strong. Should I get a dual pump or just a
single for the hot? Does it matter where I place it? Ideally I would
like to put it behind a tumble drier in the downstairs kitchen. Do you
leave these pumps on all the time or do they have some mechanism that
turns them on when you want a shower?

Thanks for help