Even if the valve you have installed is in good shape and fits your new shower installation, it's helpful to understand what type it is. Two designs typically meet modern plumbing codes ...

First, here are the tools you need: One shower shutoff valve, one roll of Teflon pipe tape, and one pair of vice grip pliers. The total cost of this project was $5, the cost of the valve itself.

If you have access to the wall outside the shower, cut through the drywall to get to the valve. If you make a careful cut, you should be able to replace the same piece of drywall when you are done.

Matthew PK answers: The shower temperature changes when you flush (or use water) because the pressure in that supply line has changed. This means less supply to the mixing valve in the same setting.

PM's home pros take a peeks behind the walls of your shower to show you the plumbing mechanics and tech that make your morning wake-up possible. Please, don't forget your shower cap.