Shutoff valves connect to copper plumbing pipes in one of two ways: compression fitting or sweat fitting. Identify the connection type used in your home by referring to the photos. If you have an older home with galvanized pipes, we suggest hiring a plumber to do the switchout. Unscrewing the old valve and screwing on a new one may seem easy enough. But if the pipe is rusted internally or the threads are rotted, this “simple” plumbing job can turn into a plumbing nightmare. If your home is plumbed with PEX or plastic pipe, these instructions don’t apply.
Once you identify the connection type, buy a quarter-turn shutoff ball valve to match the size of the incoming copper pipe and the size of the supply tube connection. If you’re replacing a sweat valve, you’ll need a torch, flux, solder, emery cloth, wire brushes and a flame protection cloth to shield the wall. This is also a good time to replace an old supply tube and a corroded escutcheon (wall trim plate).
Sweat Valve: A sweat shutoff valve doesn’t have any hex flats where the copper tubing enters from the wall. Replace a sweat valve with another sweat valve or a compression valve.
Compression Valve: Examine the portion of the valve closest to the wall. Look for a hexagonal compression nut and matching hex flats on the body of the valve next to the compression nut. If the valve has a compression nut but no hex flats, look for two flats on the sides of the valve body.
Shut off the water at the main shutoff valve. If you have a gas water heater, turn the knob to the “pilot” position. Shut off the circuit breakers to an electric water heater. Then open a faucet on the lowest level of your house and another faucet on an upper level to drain the pipes. Then disconnect the supply tube from the shutoff valve. Replace the valve.
Close the new valve. Then open the water-main shutoff valve and let the water run until all the air is out of the pipes. Then shut off the upper and lower faucets. Check the new valves for leaks. Turn the water heater gas valve back to “on” or flip on the circuit breakers to the electric water heater.
Hold the valve with a pliers, loosen the packing nut and unscrew the entire valve stem. Peek inside and remove the old washer if it’s stuck on the seat. Removing the valve stem allows any remaining water to drain out, making the unsweating process easier. Before you do any torch work, make sure there’s a fire extinguisher nearby and safeguard the wall with a flame protection cloth. Then remove the old valve (Photo 1) and the remaining solder (Photo 2).
Clean the tubing with emery cloth. If you’re replacing a sweat valve with a compression valve, sand off all traces of solder before adding the new escutcheon, nut and sleeve. Otherwise, remove enough old solder to allow the new sweat valve to slide onto the tubing. Remove the stem and wire-brush the opening in the new quarter-turn valve and apply flux to the valve and the copper tubing. With the flame protection cloth in place, heat the valve just enough to draw in the solder.
To remove a compression-style valve, hold the valve body with an adjustable or open-end wrench, or a slip-joint pliers. Grab the compression nut with another wrench and turn it clockwise to loosen it. Then pull the valve off the copper tubing.
Next, remove the old compression sleeve and nut. Grab the old sleeve with a pliers, using minimal pressure to avoid distorting the copper tubing. Then rotate and pull it off the tubing. If the sleeve is stuck, saw it (Photo 3) and break it (Photo 4).
Slide the new escutcheon and compression nut onto the copper tubing. Then add the new compression sleeve (Photo 5). Insert the new valve and apply a very light coating of pipe dope to the compression sleeve. Next, screw the compression nut onto the valve until snug. Hold the valve with a wrench or a pliers and tighten the nut a one-half to three-quarters turn (follow the manufacturer’s tightening instructions). Connect the supply tube and test for leaks.
Can you use a push-fit valve?
Several companies make quarter-turn push-fit ball-style shutoff valves that install without tools. They’re a good alternative to sweat and compression fittings if you have enough tubing projecting out from the wall and if that tubing is in good shape. They make the job even simpler. If your stub-out tubing is perfectly symmetrical, long enough and has a square-cut end, you might be able to use a push-fit valve to replace your old compression or sweat valve.
Most push-fit valves require at least 1 in. of stub-out tubing. So measure the length of the stub-out and refer to the valve manufacturer’s length requirements before buying. If your tubing will work, shop for a valve that meets your configuration needs (straight or angled). Push-fit valves are available with and without a permanently mounted supply tube. We don’t recommend the permanently installed supply tube version because you have to shut off the water and replace the entire unit if the supply tube ever needs replacement.
Before installing a push-fit valve, remove any burrs from the open end. If you’re replacing a sweat valve, remove all traces of solder and ensure the tubing is perfectly round. Then mark the installed length on the tubing and push the valve onto the tubing until it reaches the mark.