To replace a shower valve, remove the valve trim, then remove the old valve. Install the new valve by cleaning the pipes, removing the plastic cartridge from the valve, applying flux and inserting the pipes. Use a torch to solder the connections.
- Remove the trim
Remove the knob and surround from the old valve.
- Remove the valve
If possible, use a utility knife to enlarge the hole behind the surround, then remove the valve. Otherwise, use a close-quarters hacksaw to cut through the copper to remove the old valve. Cut as close to the valve as possible to preserve pipe for the new connection.
- Clean the pipes
Remove any copper shavings and corrosion from the pipes using emery cloth.
- Remove the cartridge
Remove the plastic cartridge. To replace the cartridge later, note the method of removal.
- Install the new valve
Determine the orientation of the valve, and install the fittings to make the connection. Paint the pipes and fittings with flux, and push the copper into place.
- Solder the connection
Use a propane torch to heat the connections, working one connection at a time. Once the copper is hot, touch the solder to the copper, and allow the solder to fill the joint.
- Complete the job
Once the valve is cool, insert the plastic cartridge, surround and knob.