Step 6 · Install New Single-Handle Valve
This is the most technical step. Start by thoroughly cleaning the ends of all copper pipes and the inside of all fittings using an emery cloth and wire fitting brush. Apply a thin layer of plumbing flux to all cleaned surfaces. Assemble the pipes and fittings onto the new valve body. Using a propane torch, heat each joint until it is hot enough to melt lead-free solder, allowing the solder to be drawn into the joint to create a permanent, watertight seal. Work quickly and confidently. Once all connections are soldered, mount the valve body to the wood blocking you installed, ensuring it is at the correct depth relative to the finished wall surface (use the plastic plaster guard included with the valve as a guide). The hot supply connects to the 'H' side, cold to the 'C' side, the top outlet goes to the shower riser, and the bottom outlet (for a tub spout) must be capped with a soldered cap or threaded plug if this is a shower-only installation.