It takes a short time and just a few tools to remove and replace a faulty shower valve. The shower valve controls the flow and temperature of the water that goes through the showerhead. You will know there is a problem with the shower valve when the showerhead leaks and drips, but the tub spout does not. The control knob may also tighten, becoming hard to turn. Follow these guidelines below to remove and replace your shower valve in a single-handle tub and shower control faucet.
Purchase a New Shower Valve Cartridge
Note the make and model of your shower/tub control faucet and purchase a new cartridge. For this type of single-handle faucet, the shower valve cartridge is a single-piece brass cylinder. Also purchase a new liner for the control faucet, as the leaking indicates the old liner will be seriously worn. If a liner is not available for your model of the faucet, buy a 1-yard length of weather-stripping to make a new liner.
Turn Off the Water Supply
Shut off the water to just the bathroom or to the whole house as needed.
Remove the Shower/Tub Control Faucet
Slip the blade of the flat-head screwdriver under the edge of the plastic base rim for the control knob. Twist the shower/tub control knob clockwise to remove it. Release the large metal cover plate for the faucet assembly by undoing the screws with the Philips screwdriver. With the needle-nose pliers, extract the retaining clip from the front of the valve housing.
Remove the Shower Valve Cartridge
Screw the control knob back into the housing and pull firmly straight out of the wall in order to pull out the shower valve cartridge.
Replace the Shower Valve Cartridge
Detach the control knob from the housing and pull the shower valve cartridge off. Attach the new shower valve cartridge and reinsert the cartridge and control knob housing back into the wall.
Reassemble the Shower/Tub Control Faucet
Clean any accumulated calcium or lime from the tiles and the back of the cover plate. Line the cover plate with the new liner. Make a new liner from self-adhesive weather-stripping by measuring the depth of the cover plate edge and cutting the strip to the correct width and length. Remove the back coating and press the weather-stripping onto the back of the cover plate. Give the strip a few moments to seal tightly then reattach the cover plate to the control faucet housing. Reattach the control knob and base.
Test the New Shower Valve
Restore the water supply to the bathroom and turn on the faucet to check for leaks.
Caulk Around the Faucet Cover Plate
To minimize damage to the tiles from future leaks, place a thin strip of silicone caulking around the faucet cover plate. Press it into place with the putty knife and wait 12 hours for the silicone to harden before using the shower.