I have installed a new tub and had a plumber install new taps. They are Moen. They are supposed to be pressure balanced. When the toilet flushes, we get only hot water. I went to the hardware store and got a new insert thinking that may be the problem. It did not change anything. The plumber only changed the pipes close to the tub to flexable. No other pipes were changed. My old tub did not do this, I use to lose pressure, but the water did not go hot. Any suggestions?