Replace a valve on an above-ground pool by shutting down the pool pump and draining the valve of water. Use PVC cutters to remove the valve, then install the new valve by attaching it to the PVC pipes with couplers.
To begin, toggle the pool pump to the off position, then also turn the switch on the valve off to minimize excess water flow. Open the drain port at the bottom of the pump system and let it thoroughly drain of water.
Cut the inlet and outlet pipes to the valve, using PVC cutters, allowing for room for the couplers to be installed. Typically, the gap should be less than 6 inches. Complete the removal by unscrewing the unions between the valve and the pool pump. Remove any other clamps holding the valve in position and set the old valve aside. Install the new valve using PVC couplers and attach it to the pump, then turn the pump back on.
Before replacing the entire valve, it can be checked for worn gaskets in need of replacing. To do this, turn off the pump and release the pressure inside the filter system. Unscrew the top of the valve and lift out the key stem assembly. The spider gasket is housed within the body of the valve; check it for wear and tear. If it is defective, remove it with a sharp screwdriver. The replacement gasket is glued in flat side down, with the ridged side facing up. Once firmly in place, reassemble the valve and turn the pump back on.