Turn off the water supply to the shower
Open a faucet to relieve pressure
Remove the shower handle and trim plate
Access the valve by removing any cover or wall access panel
Inspect the valve type and take note of pipe connections
Disconnect the old valve from the water lines
Remove any retaining clips, screws, or mounting brackets
Take out the old valve body
Install the new valve in the same orientation
Secure the new valve with brackets, screws, or clips
Reconnect the water supply lines
Install new solder joints, compression fittings, or threaded connections as required
Turn the water supply back on slowly
Check for leaks at all connections
Flush the valve before reinstalling the trim
Reinstall the trim plate and handle
Test hot and cold operation and verify proper water flow