i have had a new mira sport 9.5kw shower fitted, as the old one was lower power i had a spark rewire it. He did the shower swap on the understanding the old plumming would be used (so straight swap) The new shower gets either very hot or cold and won't maintain a steady temp. The water pressure seems ok ie when you turn cold taps on lots of water comes out of the cold taps very quickly. Any ideas? My thoughts are the origional pipe set up is at fault. It has a T piece from the cold bath supply pipe and an elbow connected to that on a very short (50mm) pipe, then straight up to the shower. Could this be the problem?