Before starting, turn off the main water supply to prevent flooding. Then, open the shower faucet to drain any remaining water from the pipes.

Carefully remove the old shower valve and faucet handles. If stuck, apply penetrating oil and allow it to sit for a few minutes before attempting removal. Use the appropriate tools (screwdrivers, pliers, Allen keys) to loosen and detach the components.

Measure and carefully cut the copper pipes to the correct length for the new valve. Ensure proper alignment and slope for drainage. Apply flux, then solder the connections using a propane torch and lead-free solder. Maintain proper ventilation and safety precautions.

Install the new shower valve according to the manufacturer's instructions, ensuring proper alignment and secure fastening. Dry-fit the valve first to confirm proper fit and make any necessary adjustments before final installation.

Connect the faucet plumbing to the new shower valve using appropriate fittings (e.g., SharkBite). Ensure tight connections to prevent leaks. Use plumber's tape or sealant on threaded connections as needed.

Slowly turn the water supply back on and carefully inspect all connections for leaks. Tighten any loose fittings as necessary. Let the water run for a few minutes to ensure everything is secure.