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Old 06-01-2009, 01:33 PM   #1
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Check valve and foot valve on same well feed?


I have a shallow well jet pump with approx 100' of 1-1/4" feed, with foot valve at the well end. I fired it up and got good prime - but could not hold 40 lb pressure (pump hit 40, kicked off, so far so good, then the gauge slowly dropped off)

I discovered a bad coupling in the line (which I replaced and I think I've fixed - will test when everything is bolted back together)

Question - since I'm into this project now, would it be a good idea to add a check valve on the intake line a couple feet from the pump (in addition to the existing foot valve out in the well)? Thinking this might take the pressure / strain off the foot valve (and the rest of the line - e.g. other couplings) - and save me some grief / digging later on? Or will this backfire on me by preventing the foot valve from closing properly, or some other problem I didn't think of? Is this generally a good or bad idea?

Any feedback appreciated - thanks...

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Old 06-01-2009, 08:56 PM   #2
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Check valve and foot valve on same well feed?


My advice is no. Here's why.

If the foot valve leaks any at all, and the check valve seals, the water in the pipe will be in a vacuum. Air will find its way into the pipe. Somehow. When the pump starts, it'll lose its prime.

If the foot valve is more than about 30' deep, the resulting vacuum will cause the water to boil away, leaving nothing in the upper part of the pipe. No water, no air, just nothing. Obviously, a pump won't pump nothing, so again, it'll lose its prime.

It sounds like a good idea, but the physics of it say otherwise.

Rob

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Old 06-03-2009, 01:27 PM   #3
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Check valve and foot valve on same well feed?


thanks Rob - after digging up the bad coupling - with my sore back - i just want the most reliable option to carry on. appreciate the advice
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Old 06-03-2009, 06:39 PM   #4
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Check valve and foot valve on same well feed?


In addition to what Rob said, you can't prime the line on the well side of a check valve. Also, check valves require about 5 lbs to open them (cracking pressure), and on a suction line you don't want that.

There are no short cuts in doing it right, whether the back hurts or not.
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Old 06-04-2009, 09:42 AM   #5
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Check valve and foot valve on same well feed?


Gary - thanks for the add'l info - 5lb to open a check valve - that's interesting - hope this isn't a dumb question but would that be the same for the foot valve?

it's like adding the check valve would be same effect as going to a deeper well (additional lift)?

if I let the sore back stop me I would have given up a long time ago - but I still have to grumble once in a while
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