I have a friend who says that the temp of the water coming to his two baths is significantly different and he can't figure out why. The one that is farther from the water heater provides scalding hot water. It has a single hot/cold knob. The other one, much closer to the hot water heater, has two separate knobs flowing to a single faucet. He says he can fully open the hot water knob and keep the cold water knob closed, and only get luke warm water out of the faucet. Is there possibly a cross over valve somewhere in the plumbing, or is it possible for something to be causing cold water to flow even though the cold tap is closed? Thanks.