I am pumping water half a mile through 22mm pipework at mains pressure over a hill 20ft high and it then drops 60ft where the water comes out in at varying pressures and occasionally stops for a few seconds. Could this be caused by air trapped in the pipe at the top of the hill? The water runs freely at all the other points along the line, even after the hill.

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Originally Posted by Gillett

I am pumping water half a mile through 22mm pipework at mains pressure over a hill 20ft high and it then drops 60ft where the water comes out in at varying pressures and occasionally stops for a few seconds. Could this be caused by air trapped in the pipe at the top of the hill? The water runs freely at all the other points along the line, even after the hill.

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I'm not a big pump man. In our area it's a separate trade, but let me give it a guess. Since you failed to include the pump size or the pressure it produces at the head I'm going to say that the water sometimes runs down the 60 foot drop faster then the pump can pump it up to the top. This would explain the varying pressure and the occasional lapse. Sound right to you?
Cheers, Tom

Thank you for your reply speedball 1 regarding 'airlock?'. Interesting possibility. The problem seems to have cured itself. All is well.