Hi i am going to fit a triton power shower,and would like to know if,1, how high can the hot water feed be to the shower. (i have a back boiler , hot water tank in the airing cuboard, cold tank in the loft.). 2, can i use plastic piping.3, is it allright to have 90 degree bends. My hot water tank is 4 feet from ceiling i was going to go from the hot tank into the loft then down into the shower in the bathroom. the distance from hot tank to shower is approx 7 feet.the cold tank is approx 2 feet. Can i tee of the hot water vent pipe above the vent pipe tee. thanks in aniticipation.