Step 6 · Solder New Valve
Remove the plastic cartridge from the new valve body to protect it from heat damage. Place a flame shield behind the work area to protect the wood studs. Apply a thin, even layer of flux to the cleaned ends of the pipes and the inside of the fittings. Assemble the joints. Using a propane torch, heat the fitting (not the pipe) evenly. Touch the lead-free solder to the joint on the side opposite the flame. When the joint is hot enough, the solder will be drawn into the gap, creating a seal. Repeat for all connections. Allow the joints to cool completely without being disturbed.