Step 6 · Solder and Install New Valve
With all pieces cut and dry-fit, it's time to solder. Disassemble your dry-fit connections. Thoroughly clean the inside of each fitting and the outside of each pipe end with a wire fitting brush and emery cloth until the copper is shiny. Apply a thin, even layer of flux to all cleaned surfaces. Reassemble the pipes and fittings. Remove the plastic cartridge from the valve body to prevent heat damage. Use a propane torch to heat the joint evenly. When the flux sizzles, touch the lead-free solder to the joint on the side opposite the flame. The heat will draw the solder into the joint, creating a seal. You will see a silver ring appear when the joint is full. Solder all connections. Once cool, securely mount the valve body to the 2x4 brace.