I have recently refitted my bathroom and fitted mixer taps, previous taps were single hot and cold. Ive noticed the hot water pressure is poor as its gravity fed. I have had to put none return valves on the hot supply to basin and bath as the cold water (rising main) was blowing the hot back down its pipe.The use of these valves has added further to the poor pressure though. I wondering what could be used to increase the pressure, i dont want to reduce pressure of the cold supply to compensate.