Step 4 · Prepare Piping and Mount New Valve
Now you must re-route the plumbing to fit the new single-handle valve. This is the most complex part. You will need to use new sections of copper pipe and various fittings (like 90-degree elbows) to bring the hot and cold lines from their original wide positions to the narrow inputs on the new valve. Use a tape measure to determine the lengths of pipe needed. Dry-fit all your new pipe pieces and fittings first to ensure everything lines up correctly. The new valve must also be mounted securely to a new wood brace (e.g., a 2x4) placed between the wall studs. Crucially, you must follow the manufacturer's instructions for the valve's 'setback'—the distance from the front of the valve to the front of the finished wall. A plastic depth guard is often included with the new valve for this purpose.