Is The Pump Running Dry?

[DS1]

There are a couple people working on this project, it’s on leased farm land so the history and depth of the well are unknown.

The question: what is going on when the water stops flowing, line pressure is zero, and the pump is running and pulling 4.3A. *

Background:

Pump: New VEVOR Deep Well Submersible Pump, 1HP 230V/60Hz, 37gpm Flow 207ft Head

Pressure tank: New Water Worker 44gal

Pressure switch: New 20/40. I don’t have the brand in front of me but it was purchased at a local farm supply.

Circuit breaker: New 2-pole 20A

In line pressure gauge: New, unknown manuf.

Old pump: CountyLine, 1HP, 230V/60HZ, 10GPM. Read from the pump label. This pump just flat out quit working. Even applied voltage with pump out of the well and it’s dead. No idea of the age.

2 weeks ago the water level was 129’ below the top of the case. I measured this myself.

The pump is at least 140’ down the well. The actual measurement wasn’t acquired.

I pressurized the new pressure tank to 18psi. I read that’s the procedure for when the pressure switch is a 20/40.

Pipe comes out of the well as 1”, then Ts to the pressure tank with a gauge on the T, then goes to a hose bib, then feeds a stock tank with an inline shut off valve and a float shut off valve near the top of the stock tank.

Running just the hose bib: the entire system functions as designed. Pump has perfect line and load voltage and pulls 5.5A when running. The pressure switch opens at 40psi/pump stops running and the pressure switch closes at 20psi/the pump starts pumping. When I open the hose bib the line water pressure slowly drops from 40 to 30 and stays there. The other day I ran this for just over 1.5hrs and there were no problems.

* Running just the stock tank feed: Starting with the line water pressure at 40psi, I open the stock tank shut off valve and the line water pressure immediately drops to 20psi and the pump starts and is pulling 6.1A. Water comes out of the stock tank float valve for about a minute then stops when the line pressure reads zero. At this time the pressure switch is closed, pump is running, and line/load voltage is perfect. Pump is pulling 4.3A.

Immediately opened the breaker to prevent the pump from burning up. Wait 5 mins, close breaker and water starts flowing for about 30 secs. then stops. Do it again but wait 10 mins and water flows for about a minute, then stops.

My SWAG because I'm not a plumber: the stock tank float valve has a greater demand than the hose bib, and the water level in the well drops and/or the well can’t provide enough water to meet the pump’s demand, so the pump runs dry.

Thank you.

 

[FredG]

That pump will have a hard time reaching 40psi from 140+ feet, if it can even do it, but it sounds like you are drawing the water level down to where it pumps the well dry.

 

[Sponsor]

 

[DS1]

That pump will have a hard time reaching 40psi from 140+ feet, if it can even do it, but it sounds like you are drawing the water level down to where it pumps the well dry.

Thanks Fred.

That's my non-plumber SWAG also; we're pumping the well dry.

Just to be clear as it might've gotten lost in my wall of text there:

The old pump worked just fine (until it didn't) and reached 40psi, old pressure switch opened, etc. It was 1HP and 10GPM. I replaced that pressure switch in Sept 2024.

The new pump is 1HP and 37GPM and will reach 40psi, new pressure switch opens, etc. and:

1. Will pump water all day long through the hose bib. Line pressure will sit right around 30psi.
2. But through the stock tank valve, water only flows for about a minute, pump is pulling 6.1A, and you can watch the pressure gauge zero out. When it hits zero the water stops. Pump is still running and pulling 4.3A.

I also wonder if the old pump at 10GPM was a better match for the well than the new pump at 37GPM.

 

[Reach4]

then feeds a stock tank with an inline shut off valve and a float shut off valve near the top of the stock tank.

Try mostly closing the inline shutoff valve to reduce the flow to maybe 2 gpm. Play with the setting so that the pressure stabilizes at about 35 psi while the stock tank is filling.

The hope is that that prevents the well from running dry. But if the well still runs dry, throttle the flow more.

 

[Bannerman]

New VEVOR Deep Well Submersible Pump, 1HP 230V/60Hz, 37gpm Flow 207ft Head

As that pump is capable of only 207 feet of head, the maximum pressure it is capable of developing is only ~89 psi. A low head rating is common for a low HP but high volume (37 gpm) pump as the number of pumping stages will be few, which will increase the total possible flow rate, but also limits the maximum pressure (head) possible.

89 psi minus the 40 psi pressure switch setting, provides 49 psi capacity remaining, which is equal to lifting water ~113' vertically within the well.

You said the measured water level was 129' below the top of the casing, but it is not clear if this was measured after water had been pumped from the well, or before any water had been drawn. A pump will only lift water from the top of the water level, so if the initial water level had been less than 113' from the top, that could explain why the pump could have achieved 40 psi at the pressure switch, but the pump could not satisfy the 40 psi pressure switch setting once the water level had been pumped lower.

When the pump's head capacity is exceeded by the water level dropping too low, the pump will continue to operate, but will not be able to discharge water to the surface. This seems to be the case in your situation as the pump continues to draw 4.3 amps, which signifies the pump is running, but is not able to provide sufficient lift to push water to the surface. It's likely, the pump is only able to push water up close to the top of the vertical drop pipe, but no further. It's common for a pump to draw less amps when the flow rate is low or stopped since the pump will be performing less work.

Because water will not be flowing past the pump's electric motor, continuing to run the pump with no delivered flow, will typically cause the motor to overheat within a short time. Shutting off power even briefly, will often permit the well a little time to recover, which may allow the well level to rise sufficiently to permit the pump to supply some water Once pumped lower and the pump's head capacity is again exceeded, flow will again stop.

It is clear, that pump is not the best suited for your application.

Suggest pulling out the pump, then measure the well's total depth. A lower flow rate, higher head capacity pump should ensure 40 or higher (60+) psi will be achieved reliably, even if the water level is regularly pulled down to 129' or lower. If possible, to increase the well's potential useable capacity, locate the new pump at greater depth if there is sufficient distance remaining below the current 140' pump depth.

 

[DS1]

Try mostly closing the inline shutoff valve to reduce the flow to maybe 2 gpm. Play with the setting so that the pressure stabilizes at about 35 psi while the stock tank is filling.

The hope is that that prevents the well from running dry. But if the well still runs dry, throttle the flow more.

Yessir that is what the plumber did. I do believe he's still experimenting.

 

[DS1]

You said the measured water level was 129' below the top of the casing, but it is not clear if this was measured after water had been pumped from the well, or before any water had been drawn.

Bannerman thanks for all the info in your entire post. Like I said I'm not a plumber so I need to take some time and read and understand it...and pass it on to our plumber.

To answer your question above: We pulled the pump on 18 Oct, and I measured that on 20 Oct. So it was 2 days of zero activity in the well.

 

[DS1]

Today I did the math based on the length of wire we used, length of the pump cord, etc. and my best guess is the top of the pump is at 153'6".

I've passed all this info on to the folks in charge and the ball is in their court now.

So I'd like to say thanks for sharing the info with me.

 

[Valveman]

As was said, a pump with a max head of 207' (89 PSI) cannot build to 40 PSI to shut off from 125' (54 PSI) deep. A 1HP should draw 9 amps. 5.5 amps is only a 1/2HP load. But it is the 37 GPM impellers that are the problem. Even a 1/2HP with 10 GPM impellers can work and should draw 5 amps at that depth and pressure.

 

[Reach4]

That pump will have a hard time reaching 40psi from 140+ feet, if it can even do it, but it sounds like you are drawing the water level down to where it pumps the well dry.

If the pump runs the well dry, it has enough lifting power to run the well dry.

If the pump does not have enough lift capacity for the desired flow+pressure, then expect the flow to stablize to whatever gpm with the water level at some level higher than running dry. That gpm will stabilize at the replacement rate of the well. If the replacement rate is way too low, expect the pump to overheat and fail. A flow inducer will help keep the pump motor cooler.

The new pump is 1HP and 37GPM and will reach 40psi, new pressure switch opens, etc. and:

NO, it won't. They spec their pumps in a misleading manor. That pump is rated to do 37GPM OR will reach a pressure. I think they are saying to expect (37 gpm at 0 psi (zero lift)) OR (will push water up 207 ft at near-zero GPM). You would need to find a pump curve to understand what to expect.

 

[FredG]

2. But through the stock tank valve, water only flows for about a minute, pump is pulling 6.1A, and you can watch the pressure gauge zero out. When it hits zero the water stops. Pump is still running and pulling 4.3A.

If the pump runs the well dry, it has enough lifting power to run the well dry.

 

[Fitter30]

Running the pump dry is very hard on it. Motor over heats and seals burn up.

 

[FredG]

Running the pump dry is very hard on it. Motor over heats and seals burn up.

At least it’s only a $150 pump.

 

[Fitter30]

At least it’s only a $150 pump.

They do make pump savers but their over $300

 

[DS1]

Thanks for the continued info.

Apparently there's now a PVC leak they're working on.

My concern now is there are too many cooks in the kitchen. I'm worried someone will go out there, turn the brkr on, the water stops flowing, they leave the brkr on and burn the pump up.

Guess I could put a LOTO on it but this is out in farm country and someone would just pry it off.

 

[Fitter30]

They do make pump savers but their over $300

But if and when you want water and there isn't any. Going to do with out when a pump saver might have done its job.

 

[Valveman]

A Cycle Sensor is watching 24/7 for a dry well condition. The cost of the pump is not as much an issue as being out of water because the pump ran dry and burned out.

Cycle Sensor Pump Monitor – Cycle Stop Valves, Inc

Buy It! Interactive Animation General Information Specifications Wiring Diagram Installation Instructions Installation Video Troubleshooting

cyclestopvalves.com

 

[DS1]

Interesting. Thanks for that.

I'll pass that along and will probably research others also.