- if the suction side of the pool pump pipe-work is not completely full of water, i.e. if there is air in the line, the pump may lose 'prime' and will not pass
any water.  This is because pumps are designed to PUSH water and not to PULL air.  (Airlocks are particularly common when a pool has been drained and refilled)

Airlocks can be cleared by using the pump, plus the water in the pump and any water in the line, to create a vacuum and thereby draw water up the air-locked line and into the pump, but it's a good idea to check up on a couple of things first to make sure that air is not being constantly drawn into the pump or the suction line

• Check the 'O' ring or gasket of the pump-strainer lid. Make sure that it is a good fit, has not expanded or gone out of shape, and is not damaged in any way. If necessary, buy and install a new 'O' ring or gasket

• Make sure that the compression screw-ring connectors on all suction-side valves (Bottom Drain, Skimmer and Vacuum) are done up tightly

•  These valves are sealed by compression of a rubber 'O' ring gasket and, over time, the rubber can become 'flattened' and allow air to be drawn in when the pump is running

How to clear an airlock

• Close the Bottom Drain, Skimmer, Jets and Vacuum valves and remove the lid of the pump housing to get at the strainer basket

• Check that the strainer basket is empty, then replace it

• Fill the pump housing with water and replace the pump housing lid

• Set the Rotary valve to ‘Filter’, open the Jets valve.  Now comes the tricky bit; timing is critical

• With the valves set as described above, switch the pump on and open the Bottom Drain valve at the same instant

• Listen, or watch, for water coming into the pump as it is drawn up the pipe-work

• When no more water comes into the pump close the Bottom Drain valve and then switch the pump off.  Do it in that order to retain the water that the pump has raised so far and to prevent it draining back into the pool

• Refill the pump housing with water as detailed above and replace the lid.    Start the pump and open the Bottom Drain valve at the same instant

• Watch or listen for incoming water and, once it stops, close the Bottom Drain valve then stop the pump

• Repeat these simple steps until you have cleared the airlock

• Once you have the water flowing through the Bottom Drain line, slowly open the next valve on the suction side and allow the pump to remove air from that line, etc.

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Ken Walker - MyPoolGuru©