Any pool configuration has two basic piping systems: suction and return. The suction side consists of all the pipes coming from the pool to the pool pump. In a basic system these include the pipes from the main drain and the skimmers. The return or discharge side consists of all pipes going from the pool pump back to the pool. In a basic system these include lines to multiple pool jets. On the suction side you will want to be able to control the flow of water coming from either the skimmers or the main drain. This is done with a diverter valve. This page will provide a step by step process for installing a diverter valve on the suction side of the pump.
A 3-way Diverter Valve is assembled at the manufacturer so that the valve operates between the two ports away from the inlet port. In the picture at the left, the valve handle is turned all the way counter-clockwise to stop and close off the left port (skimmers). Water will only flow from the right port (main drain) through to the inlet port going to the pump.
In this picture the valve handle is turned all the way clockwise to stop and close off the right port (main drain). Water will now only flow from the skimmers to the pool pump. In either case the handle cannot be turned pass the stops to shut off the inlet port. This is important because if the inlet port is shut off, no water can flow to the pump: the pump will run dry and start to generate dangerous internal pressure.
When installing a value, you must first remove the internal valve assemble before gluing the valve body to the pipe. This will ensure that you don't accidently glue the internal valve parts together. To remove the internal valve assembly, first loosen the lock knob on top of the handle and move the handle halfway between the two uppper ports. This will make it easier to pull the assembly out of the valve body. Now remove all 8 screws.
The next step is to cut the pipe to the length required. Remenber when measuring the length of the pipe, allow an extra 3\4 " to 1 1/2 " on each end for the overlap into the fittings (varies by fitting). You can use a regular hacksaw to cut the pipe. Just try to cut the pipe as squarely as possible.
Now you are ready to attach the pipe. This is usually a two step process. First put a thin coat of purple primer on both pieces to be joined: inside the port and the outside of the pipe. Make sure that all joining surfaces are covered and make sure that no primer enters the valve body beyond the ports. After the primer has dried, reapply the two surfaces with Universal CPVC glue. Again make sure that no glue enters the valve body beyond the ports. The CPVC glue and purple primer are usually sold together as a kit.
Repeat Steps 8 - 11 to add pipes to the other two ports.
Complete the valve installation by attaching the three pipes coming out of the valve to their suction pipes. You will probably need to add 90 degree elbows to the pipes coming out of the ground from the skimmers and main drain. The picture at left shows the end result of a typical valve installation for a basic pool.