With a little plumbing knowledge and a well-situated access panel, replacing a shower/tub faucet is a doable fix-it project.
Step 1: Faucets are not universal. Select one that is the same size and similar in design to the old faucet. For two- or three-handled faucets, measure the handles from center to center. Also consider the length of the faucet stems in correlation to the depth of the wall.
Step 2: Turn off the water supply at the main shut off valve and open the faucet handles to drain any remaining water in the pipes.
Step 3: Remove the old faucet, being careful not to jar or twist the existing pipes. If the faucet has been soldered on, it is possible to heat the solder joints and work the fittings apart. Using a tubing cutter to cut the copper just below the fitting may be an easier method of removal.
Step 4: Detach the shower/tub handles from the new faucet valve by removing the handle screws.
Step 5: Follow the manufacturer’s instructions for installation of the new faucet. Use Teflon tape or pipe thread compound on all threaded pipe joints, but not on any compression fittings.
Step 6: Attach the water supply lines to the new faucet. Use an adjustable wrench to assure the coupling nuts are thoroughly tightened.
Step 7: Attach the shower riser to the faucet. For threaded applications, use a union fitting or detach the shower head and arm assembly from the shower riser before screwing the riser into place.
Step 8: Attach the tub spout extension to the faucet valve and install a nipple for the tub spout to attach to. Tentatively position the faucet valve into place to assure the tub spout nipple extends the appropriate distance through the wall per the manufacturer’s instructions.
Step 9: Complete the shower/tub faucet installation by attaching the shower arm, tub spout and handle escutcheons. Slip the faucet handles into place, but do not attach them.
Step 10: Turn the water supply on and test the faucet and fittings for leaks. Let water run through the tub spout and the shower arm to clear any debris that may have been jarred loose within the water lines.
Step 11: Attach the faucet handles, install the shower head and prepare to take a long hot shower or bath … you’ve earned it!