hi forgive my ignorance i want to buy a good powerful shower for my upstairs bathroom i have a vokera linea gas combi boiler . i would like to add that my hot water pressure is nt the greatest up the stairs especially if a tap is switched on or washing machine is going, it turn s to trickle . so is it possible to get something that can run directly off the cold tap which is powerfull all the time. please help 
