Jet Pump fast cycle

I pull water from a lake and pump it up to my cottage. For some reason, my pump has started short cycling. I changed the pressure switch, and the pressure tank is fully charged (about 38 lbs). It is primed. If I open the prime port and turn the pump in it shoots water high into the air - getting water is not the problem.
When the pump comes on, it quickly builds pressure to 40 lbs and then shuts off, pressure immediatley drops to 20, pump comes on, then off very rapidly. Would a leak in the line between the jet pump and the house cause this? I am thinking it might have frozen and split....
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I pull water from a lake and pump it up to my cottage. For some reason, my pump has started short cycling. I changed the pressure switch, and the pressure tank is fully charged (about 38 lbs). It is primed. If I open the prime port and turn the pump in it shoots water high into the air - getting water is not the problem.
When the pump comes on, it quickly builds pressure to 40 lbs and then shuts off, pressure immediatley drops to 20, pump comes on, then off very rapidly. Would a leak in the line between the jet pump and the house cause this? I am thinking it might have frozen and split....
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You need to charge the tank with the pump off and a faucet open. Sounds like you're water logged.
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Steve Barker




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wrote:

Pressure tank is charged to 38 Lbs, and not heavy - so assume not water logged. That's why I was suspecting a leak.
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On May 10, 8:06 pm, snipped-for-privacy@gmail.com wrote:

Check valve? Tom
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On 10 May 2007 20:06:43 -0700, snipped-for-privacy@gmail.com wrote:

It's easy to detect a leak. Shut off everything in the house. Preferably shut off the main valve in the house (if there is one).
Pump up to full pressure, then watch the pressure gauge. If it slowly drops, you got a small leak. If it drops quickly, you got a big leak.
I also think you are waterlogged. Empty the tank completely and drain the lines. NOW check the tank air pressure. Close all drain valves and restart the pump.
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On May 11, 8:49 pm, snipped-for-privacy@nomail.com wrote:

The pressure in the bladder should be 2lbs less than what ever you want the pump to turn on at. Check the air valve if you have water replace the tank
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On Thu, 10 May 2007 19:44:21 -0700, 020SHC wrote:

Does the tank have a bladder?
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Or the foot valve (if any) could be bad.
Bob
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On 10 May 2007 19:44:21 -0700, snipped-for-privacy@gmail.com wrote:

First, your pressure tank should be charged to 2 lbs less than the cut *in* pressure. So if your pump comes on at 20, the tank should be charged to 18 when completely empty of water. If your cut-in pressure is 40, then you're ok, but you said the pump stops at 40, so that doesn't sound right.
Try disconnecting the line to the house and blocking the end from the tank. (You should have a valve here anyway...) If it builds and holds pressure, you have a leak in the line to the house.
If it still cycles, you have a leak on the source side, or a bad foot valve or check valve.
HTH,
Paul
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On May 10, 7:44 pm, snipped-for-privacy@gmail.com wrote:

Others have covered all the points so I will just wrap it all up in one:
1. Your pre-charge tank pressure is too high. Drain tank and re- charge to 20 psi. If the problem stillpersists:
2. Leak? Quit possible, in the input line or a footvalve or check valve. You can install a new checkvalve just prior to the tank. It will work just fine.
I have assumed (I know, I know) that the pressure tank is in the cottage. If it is co-located with the pump then the leak could be on the house side and in that case you will have to find and fix it.
Harry K
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On May 10, 7:44 pm, snipped-for-privacy@gmail.com wrote:

Others have covered the problem and solution. I am just wrapping it all up in one:
I am assuming the pressure tank is in the house:
1. Your pre-charge in the tank is too high. Drain tank and re-charge to 18psi. If that doesn't cure it, then you have a leak.
2. The leak will be either in the inlet pipe to the tank. It can be a broken pipe, a bad footvalve or a check valve. You can fix the problem by installing a new checkvalve just prior to the tank. The system will work just fine as long as the pump doesn't loose prime but if it is a broken pipe you will be pumping a lot of water out of it every time the tank fills. May not matter
Now if the tank is co-located with the pump, then you have to find the leak and fix it. Start witht he foot valve. If it is in the pipe going to the cottage, you'll have to dig it up and fix.
Harry K
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