A diverter valve works very much like a gate. Water enters the valve from the water supply line, and the diverter valve directs or "diverts" the water to the appropriate water outlet. When the diverter valve is open, the water exits from the bathtub's spout. When the diverter valve is closed, water is routed to the shower head. If the diverter valve tends to stick, or water continues to exit the bathtub's spout instead of the shower head, the valve must be replaced.
Turn off the water supply at the main shutoff valve near the water meter.
Remove the diverter valve's handle by removing the single screw in the centre of the handle with a screwdriver, then sliding the valve's handle off the valve's stem.
Remove the screws that hold the escutcheon plate in place against the wall with a screwdriver, then remove the plate from the wall to reveal the valve.
Remove the bonnet nut used to secure the diverter valve with either an adjustable wrench or channel-type pliers, then remove the diverter valve by unscrewing the assembly with an appropriate-sized deep socket and a socket wrench.
Coat the rubber stem washer located at the back of the replacement valve with heatproof grease. Insert the replacement diverter valve into the wall, then tighten the valve into place with the deep socket and socket wrench. Slide the bonnet nut over the valve's stem and tighten the nut with either the adjustable wrench or channel-type pliers.
Place the escutcheon plate over the valve, then slide the plate's retaining screws through the plate. Tighten these screws with a screwdriver.
Slide the diverter valve's handle onto the valve's stem, then insert the handle's single screw through the centre of the handle and tighten the screw with a screwdriver. Turn the water supply back on to complete the replacement.