I recently bought a house and in the master bathroom the hot and cold water seem to be reversed. When I turn the dial left, the hot water comes out first with very little pressure. As you continue to turn the dial left, the water pressure goes up but with it comes cold water. I've read you can turn the valve 180 degrees, but I'm not sure if my shower fits that method. Took a photo with the dial off. Any help is appreciated. Thank you, 
Plumbing – Hot water and cold water switched in shower
plumbingplumbing-fixturerepairshower
Best Answer
I did this a while ago in my shower. I can't remember exactly, but that stem sticking out is part of a bigger cylinder/canister that fits inside of the big pipe. When I did it I worked the whole canister out of the pipe (it was stuck in there pretty good), took a look at it and played with it until I got the right rotation.
Like Daniel suggests, you want to make sure each limit of the movement is fully hot or fully cold. If you get it wrong you can miss the full range, or even have a dead spot in the middle with hot and cold on either side.
It looks like you have to take the front cover of that pipe of to get the canister out. Have fun.