Removing the Valve

• 1
  Typical main water valvewater meter image by jimcox40 from Fotolia.com
  
  Find the main water valve for the system and turn it off.
  
  
• 2). Bleed the system of pressure by turning on all the sprinkler valves. If the valve is electrical, disconnect the two wires to it.
  
  
• 3). Clear away any debris or dirt that obstructs your ability to work on the valve. Ideally, expose 12 to 18 inches of pipe on both sides of the valve to allow for the movement of the pipe.
  
  
• 4
  PVC pipe cuttercutting tool image by Greg Pickens from Fotolia.com
  
  Cut one of the pipes about 2 inches from the existing valve, using the cutters. There may be a sudden rush of water; this is normal, as the pipe may still contain water. If the valve is in a hole and the hole fills with water, use the hand pump to remove the water.
  
  
• 5
  Slip jointed 90-degree couplingspvc image by pearlguy from Fotolia.com
  
  Unscrew the existing valve from the remaining pipe, if it is threaded. Be careful not to let dirt into the pipes. If the valve is slip jointed (smooth), cut the other pipe with the cutters about 2 inches away from the valve.
  
  

Installing the New Valve

• 1). Wrap Teflon tape on the male end of the existing pipe, for a threaded valve, making sure to make at least one complete wrap.
  
  
• 2). Screw a new valve on the pipe. There will be an arrow on the valve; make sure it points in the direction of the sprinklers, which is the direction of water flow. If the valve is slip jointed, apply primer to a rag and clean the valve and the existing pipe. Then apply the cement to the valve and the pipe. Push the valve on and give it a slight twist to set it. Hold for 30 seconds. Again, make sure the arrow is pointing towards the sprinklers.
  
  
• 3). Remove the threaded piece of pipe from the old valve to reuse, if the replacement valve is threaded. Wrap it with Teflon tape, like the existing threaded coupling on the pipe. If the valve is slip jointed, clean this end of the valve and one end of the 12-inch replacement pipe. Apply cement to valve and pipe. Insert the pipe into the valve and twist to set. Hold for 30 seconds.
  
  
• 4). Align the free cut end of the pipe on a threaded valve with the existing system pipe that you cut it from. (Since you cut the reused pipe from the existing pipe, it should line up perfectly.) If the valve is a slip joint, you will need to cut the 12-inch replacement pipe so it lines up with the existing system pipe. (Since you had to replace some of the pipe, it will be too long and will need to be cut to make it align with the existing system pipe.)
  
  
• 5). Clean the valve pipe and the system pipe with a rag and cleaner. Clean both ends of a coupling.
  
  
• 6). Apply cement to the pipe ends and the coupling. Press the coupling onto one of the pipes. Pick up both pipes and put the free end into the coupling. Set down the joined pipe and the pipe should set into the coupling. Let stand for 30 seconds.
  
  
• 7). Let the pipe cement set for 24 hours before testing the system. If the valve is electrical, reconnect the wires to the new valve. Twist on wire nuts.