In a pool plumbing system, there are pipes that bring water from the pool (suction pipes), and one or more pipes that take water back to the pool (return pipes). Pool Valves are used to control the direction of water flow, to and from the pool, and in and out of equipment. In between the suction pipes and the return pipe are the pool equipment such as the pump and filter, salt chlorinator or chemical dosing system and maybe a heater.

I have included some photos of customers pool equipment set ups above to show you different examples of setups.

I recommend once you understand the flow of the water and know the source of each pipe above the ground, at your equipment area, label them with a permanent marker. You can write the names and use arrows to show water flow direction.

Suction Side vs. Pressure Side

Now that you understand the direction of the water flowing from the pool, through your equipment and back to the pool.

In front of the pump, or specifically in front of the pump impeller, the water is under a vacuum, and suction draws it up from the pool.

Any problems in the suction side pipes or valves will leak air when the pump is on.

After the impeller, the water is now under pressure. Any void in the pipes or valves will leak water.

The water FROM the pool is under a vacuum suction, being PULLED from the pool. After the water passes thru the eye of the pump impeller, it is under pressure and is being PUSHED through the filter and back to the pool.

Pool Non Return Valves

A pool check valve is a one-way flow valve, and is used for a variety of purposes. Installed in the pipe, it only permits water to flow in one direction only.

  1. For pool systems installed above the pool water level
  2. To prevent backflow from a chlorinator into a heater or filter
  3. To prevent cycling of water in a loop, e.g. solar heater systems

3 Way Valves

As you turn the handle, you are turning the diverter, or ‘door’ which can be in a position between the two pipes, splitting the flow equally among both incoming pipes, or the valve can be turned within a range of 180 degrees, to restrict or close off, one of the two incoming pipes. An example is above where they are installed so you can control how much water (if any) is going through a pool heat pump.