A mixing valve keeps the shower from getting too hot or cold.
The mixing valve mixes hot and cold water to the appropriate temperature for one-handle shower fixtures. It may be necessary to replace mixing valves when they wear out or break, or if the water temperature does not get hot enough or is too hot and cannot be adjusted. Mixing valves may also need to be removed if the shower previously had a fixture with one handle for controling water temperature and the fixture will be replaced by two handles for controling water temperature, one handle for hot and one for cold water. Removing the mixing valve is easy for the do-it-yourselfer.
Turn off the circuit breaker for the bathroom and turn off water at the pump. All water pressure must be removed before removing the mixer valve.
Loosen the valve slightly with two pipe wrenches, one on the plastic ring attached to the valve and one on the pipe. Turn the pipe wrenches in opposite directions, with the valve wrench moving counterclockwise.
Remove the bolts securing the valve in place with an appropriate socket wrench, turning them counterclockwise.
Move the pipe wrench on the valve counterclockwise, loosening the valve the rest of the way, and remove it.