Keep losing prime or pressure

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Dylanlakepump35

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Hi everyone.
So I am running a jet pump and it keeps losing prime or pressure.
I live on the side of a lake and run our line straight into it. Our pump seems to run perfectly except it loses prime every couple weeks.
This happens during the middle of the night and leaves the pump running all night with no water until I wake up and re-prime it. I’m worried this will blow the pump.
It seems to have no leaks in the lines and I do believe the foot value is good as I was out at the end of the line a few months ago.

Could this be a pressure tank issue and how would I check if it is???
 

Reach4

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I think you are saying that your foot valve is at the end of the pipe in the lake. I think you use a Mac.

Is your pump controlled by a pressure switch, or is this controlled by an irrigation controller or other switch?
 

Dylanlakepump35

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Hah yes I do mean foot valve.

And the pump itself has a pressure switch. And the pressure switch at the pressure tank itself has been disconnected.

Could this be a problem? I didn’t set this up myself I just moved back to my family house and have been trying to fix things as I go…
 

Dylanlakepump35

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No other check values.

And there is a forked pipe at the top of the pump you open to prime. You can it in the photo. It’s the silver one
 

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LLigetfa

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It seems to have no leaks in the lines and I do believe the foot value is good as I was out at the end of the line a few months ago.
How did you come to that conclusion? A suction leak is invisible to the naked eye. A small suction leak could accumulate air at the top of the diaphragm that could survive many cycles until it grew large enough. Combined with a leaky footvalve, that accumulated air once large enough could displace the prime.
 

Chucky_ott

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Another thing to consider is the pressure your pump is able to build and the pressure settings on your switch.

If the pump can only build a maximum of 58psi and your switch is set to 40/60, the pump may never turn off.

I'm not saying that this would cause you loss of prime. But that, in addition to other issues, means that you could be chasing your tail when trying to resolve the issues.

1. check your pump specs to make sure the max psi it can build is higher than your pressure switch cutoff.
2. Make sure the only check valve is the foot valve.
3. Tighten every hose clamp on the suction line

I have a tee and a valve on the discharge port of my pump. The valve allows me to easily purge any air that may accumulate.
 

Chucky_ott

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I didn't see your pictures before. In the intake pipe, you have a ball valve. What's about 6" below that? Looks like brass.
 

Bannerman

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What's about 6" below that? Looks like brass.
Appears that it may be a check valve.

With so many connections in the suction line, there is too many opportunities for air to enter.

A top mounted check valve as suspected, may be preventing the foot valve from reliably closing fully. Any leakage through the foot valve, will cause the suction line to remain under negative pressure while the pump is not operating, which will pull in air through any leakage point.

Recommend removing the top check valve and ball valve from the suction line, to minimize the number of connections. Without the top check valve, whenever the pump is not running, the suction line will be subjected to positive pressure from the pressure tank. The positive pressure will assist the foot valve to fully close, and there will be less potential for air leakage while the pump is not running.
 

Chucky_ott

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His first post states that he has a line going into the lake. I'd expect a foot valve there but who knows. OP will have to clarify his setup.
 

Dylanlakepump35

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Hey everyone thanks for the great advice so far.
And yes chucky you are correct I only have the foot valve and no other check valves. The other brass fitting is a second ball valve for no apparent reason. ( my uncle added it ) I know I need to get rid of this and minimize connections I was just hoping to get to summer first…

The first thing chucky said makes a lot of sense, about a small suction leak allowing air to build up against the diaphragm.

Is there anyway to check for this, as you said visually will no work?
 

Reach4

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And the pump itself has a pressure switch. And the pressure switch at the pressure tank itself has been disconnected.
Given that you have a pressure switch and that you have no check valve other than the foot valve, I cannot see how the pump would lose prime. The pump should turn on, and start pumping. After the pump turns off, because pressure is reached, then the long pipe should be under pressure.
 

Chucky_ott

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The first thing chucky said makes a lot of sense, about a small suction leak allowing air to build up against the diaphragm.
I don't think that was me. My first suggestion was to check the specs of your pump to see if it can build enough pressure, at least higher than the cutoff of your switch.
 

Dylanlakepump35

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Sorry chucky you’re correct. It wasn’t you.
But yes the pump does reach 60psi and shuts off automatically.

And the suction pipe is not losing pressure at the foot valve as it would take way longer to prime afterwards. It only takes enough to fill the pump housing to get it going again.
 

Reach4

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Pump runs, you stop using water, pump stops. Pressure gauge says 60 psi. You continue to not use water. An hour later, what does the pressure gauge indicate?

If pressure switch is set to 40/60, set the air precharge on the pressure tank to 35 psi. Air precharge is measured and set with the water pressure zero.
 

Chucky_ott

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From my own experience, my own pump specs specified it could build up to 57psi. I did not know that at the time and had increased my switch to 40/60. It worked for a while but at some point, my pump would start running for a long time, never able to reach to cut-off pressure. That, in combination to a suction leak at one of the joints, caused similar symptoms to you. Eventually, the pump got so hot that the plastic fitting melted and water sprayed everywhere in my pump house. Luckily I have a low pressure cutoff on my pressure switch.

So I'd verify your pump specs to confirm its max pressure. Then tighten every pipe clamp on the suction pipe (and maybe try to remove the two valves while you are at it).

I wonder if your pump running for such a long time and dead-heading is causing water to turn to steam and introducing air somehow.
 

Dylanlakepump35

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I did do a pressure test like that about two months ago and I didn’t see any pressure lost. But I will try again and see if anything changes.
I will also minimize my connections and tighten the rest.
Thanks for the suggestion, I will give an update in a few days
 
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