Be sure that the copper pipe and fitting are clean. Sand the outside end of the pipe and the inside of the fitting with fine sandpaper, then wipe both clean with a dry rag or a fitting brush. Apply flux to both surfaces and assemble the joint. Leave one end of the pipe open to release hot-air pressure. If you must hold a piece that's being soldered, grip it with locking pliers.
Direct the flame of a propane or Mapp-gas torch to the fitting more than to the pipe. (When using lead-free solder, many professionals prefer the higher heat of Mapp gas.) Heat all sides of the fitting evenly. Then touch the tip of the solder wire to the edge of the fitting. If the pipe and the fitting are hot enough, the solder will flow rapidly into the joint. Don't over-solder the joint it won't make the bond any stronger. Allow the pipe to cool before moving it.Make sure there's no water dripping through the line when you solder. If the pipe gets hot enough, the water inside will turn to steam, escape through the joint and ruin the bond.
Tip From the ProsIf old valves don't fully shut off the flow of water, wad a piece of white bread (no crust, please), and stuff it into the pipe before soldering. The bread will hold back the water long enough for you to solder, but will flush away quickly once you open a valve and restore the water pressure.
Safety
Use a heat shield attachment when soldering near any flammable surface. Have a fire extinguisher and a spray bottle filled with water handy remember, you'll have the water turned off when you're working. Wear eye protection, a heavy, long-sleeved shirt and leather gloves.
Portions SierraHome, Copyright Sierra On-Line, Inc.
