I am taking a shower tray out and replacing it with a bath.Its a bungalow with an open vented system with a small hot water cylinder enclosed behind a stud wall .The vent pipe coming off the top of the cylinder is only 15mm and the hot distribution pipe is only 15mm.The cold pipe to the ped basin is only 15mm.Can I tee into both hot and cold pipes for the bath supply?Would I get adequate pressure from doing this?