Jet pump loses pressure intermittently

[mrbillsails]

I have a brand new jet pump with a shallow well. The well has a steel casing inside a concrete well tile. The water flows over the top of the two foot tall well tile. When the two plastic pipes to the pump in the basement are disconnected, water pours out of them.
The pump will occasionally lose pressure and either not be able to get above 40 pounds or will even just drop to zero while trying to pump. I shut off the pump for 30 seconds, turn back on, and the pump regains pressure.
The pump specialist who installed it is stumped.
My wife has had it with interrupted showers while I run to the basement to switch the pump off and on again.
We are afraid to run laundry or dishwasher when we are not home since the pump will just run forever, or until it burns out.
Thank you for any input.

 

[Reach4]

Are you in an area where they do irrigation from wells or in a desert?

They have devices to monitor the electrical current to the pump and shut the pump down when the well runs dry. Cycle Sensor is such a device. https://cpkits.com/collections/cycle-sensor-pump-monitors

You could get a clamp-around ammeter to measure the current during such an episode to measure for the tell-tale current drop.

Often shallow well is used to describe a well where the water is only 25 feet or less down. A 2-pipe jet pump, as you have, can pump from much deeper than 3o ft.

 

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[Valveman]

You probably have a suction leak right where the pipe screws into the pump. But it could also be the pump barely builds enough pressure to make the cut-out of the pressure switch. Which model pump do you have and is it a 40/60 pressure switch?

 

[mrbillsails]

Plenty of water here. Shutting down the pump when it gets in this state might save the pump, but I would rather fix the problem, whatever it is.

 

[mrbillsails]

Not sure of the model right now other than it is a Goulds with a 40/60 switch. Strange thing is that most of the time the pump works fine, builds to pressure and shuts off. When it has it's problem it could be running and running with zero pressure on the gauge. I shut it off for 30 seconds, turn back on, and then it builds right up to pressure no problem.
This usually happens when someone is in the shower.
Can water the garden for an hour with no problem.

 

[mrbillsails]

The pipes in the well have not been removed in the 18 years I have owned the house, so I don't know how deep they go, but it is essentially an artesian well, water runs right out the top unless we have run for an hour or so watering garden, then it gets down in the tiles.
Have only had it low enough, about 8 feet down, to see the casing in the center of the concrete tile a very few times.

 

[Reach4]

If you don't have the model handy, you might want to post a photo of the pump and connecting pipes.

If your water level only gets down to 8 feet, you could set this up as a single-pipe pump. This presumes that the pump is not much higher than the well top.

 

[Valveman]

A submersible would be the most reliable, as it doesn't lose prime. Which losing prime is going to be my guess. A small suction leak at the pump will work fine as long as you are using a lot of water like in the garden. But when only a shower is running and the pressure gets to 59 PSI, that pump is probably not pumping much water. Some of those pumps can only build like 60- 63 PSI. So when it gets to low flow, the suction leak takes charge and you lose prime, which is why you see zero on the gauge.

 

[mrbillsails]

The pump is a 1/2 hp Goulds J5.

 

[mrbillsails]

The pump is a 1/2 hp Goulds J5.
The top of the well over which the water flows out, is higher than the pump in the basement.

 

[Valveman]

The pump is a 1/2 hp Goulds J5.
The top of the well over which the water flows out, is higher than the pump in the basement.

Even with a flooded suction that pump can only build 63 PSI max. So when using a 40/60 switch, the flow rate just before the pump shuts off is very low, and a suction leak would make it loose prime. I think just turning the pressure switch down to 30/50 will solve the problem, but you may also still need to find and fix the suction leak.

 

[mrbillsails]

Thank you for your responses.
Do you think that the suction leak and loss of prime would result in total loss of pressure while the pump is running, showing zero pressure?
Upon shutting off the pump for 30 seconds and restarting, it runs right up to full pressure.

 

[Valveman]

Thank you for your responses.
Do you think that the suction leak and loss of prime would result in total loss of pressure while the pump is running, showing zero pressure?
Upon shutting off the pump for 30 seconds and restarting, it runs right up to full pressure.

Yep. When you shut the pump off the air bubble in the impeller will "bloop" to the top of the pump case. So when you turn the pump back on there is water in the impeller and it starts right up. The suction leak only causes a lose of prime when the pump is producing low flow rates. The higher the pressure, the lower the pump flow rate. That is one reason you do not want the cut-off setting of the pressure switch anywhere close to the max pressure the pump can build, as max pressure the pump can build means zero flow. So run the switch at 30/50 instead of 40/60 when you have a pump with a max pressure of 61-65 PSI.

 

[mrbillsails]

Thanks, that sounds like a nice simple solution. I was able to reduce the pump cut off setting. It may have reduced the frequency of the problem, but has not eliminated it. Still happens at least once, to a couple times a day. Sometimes the pump is just running with no pressure, others, it may be at 20 to 30 pounds and just can gain until I shut off the pump and give it a quick break.
I am afraid to run anything when I am not there to monitor it so I can shut it off before the pump burns out.

 

[Valveman]

A Cycle Sensor would protect the pump from running dry while no one is looking. But fixing the suction leak would keep it from losing prime.