Help! Is our submersible pump ruined?

[George G]

Hi All,

Our landscaper made a foolish mistake and we wonder if our deep well pump is permanently damaged. Here are the details:

3/4 HP Gould Submersible Pump set at 300'.
This is a temporary setup out in a field, as we wait for our house to be built.
There is a 3/4" spigot on a post next to the well, with a 100lb pressure release valve above the hose connect (in case the hose gets shut off). We connect a hose to this spigot and turn the well on and off at the breaker. We normally get about 5GMP out of the well.
We have been running it this way for over a year. Normally we run it to fill a 1000 gallon tank and then have a second pump satisfy our garden needs.

However, our tank system has been dismantled for winter, and yesterday our landscaper, not thinking, attached a 5 GPM Rainbird impact sprinkler to the direct hose line coming from the well. It ran for maybe 10 minutes before water pressure dropped dramatically, and we ran back to shut off the well. We checked the hose connections and removed the sprinkler. None of the hoses seemed to be broken, and the pressure relief valve didn't release. The well did not run dry, it was fully recharged.

We obviously stopped using the sprinkler. Then we went to dispense water from the hose normally with a sprayer nozzle like the one below.
We have done this for extended periods (2-3 hours) with no problems whatsoever. However, after the sprinkler issue, we were watering with the nozzle and about 20 minutes into the issue the same loss of pressure occurred.

Have we permanently damaged the pump? We are hoping it was a thermal shutoff, but are very anxious that something more serious happened.

Can you give us some ideas as to why this occurred and how it might have damaged the pump?

Should we avoid using the nozzle entirely and run the pump full open from now on, or is the pump fatally broken and it's only a matter of time before it gives up completely?

Thanks for your help!

 

[Valveman]

Running the 5 GPM sprinkler didn't hurt the pump, unless it pumped the well dry. The hose nozzle will put out even less than 5 GPM, but also will not hurt the pump. It does sound like you pumped the well dry in 10 minutes of using 5 GPM. The hose nozzle will probably work for 2-3 hours because it puts out much less than 5 GPM, and doesn't pump the well dry, or at least not as fast.

If the overload in the motor tripped, the pump will just magically come back on in a few minutes. But you can check with a clip around AC amp meter. 6-7 amps means the pump is making water. Less than 5 amps means you have pumped the well dry. More than 7 amps will trip the overload in the motor.

I guess it is possible the pump is set so deep it is not getting proper cooling past the motor, which will trip the overload. But still guessing it is pumping the well dry after about 50 gallons or so. The well could be re-charging fairly quickly after the pump goes off, and still not make 5 GPM.

 

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[George G]

Thanks so much Valveman, you're the guy I was hoping would reply!

The pump is set very deep, and because of the water column on top, we can usually pump for a long time before we notice the pressure start to subtly decrease, at which time I know we are drawing the well down and it's time to shut off.

We were worried we somehow created a ton of backpressure and thus damaged the pump, but I couldn't understand how the sprinkler would do that more than the nozzle...

For what it's worth, it seems like the nozzle puts out a steady 5 GPM regardless of whether it is full open or reduced.

Is it your feeling that the pump is okay? I know these things are pretty robust but I don't want to do anything that might damage it. Now we're a little gun-shy, and I'm thinking of running a 1" poly line straight to our tank so the well pump can run wide open, but I know from your posts that's not necessarily the right thing to do either...

 

[LLigetfa]

However, after the sprinkler issue, we were watering with the nozzle and about 20 minutes into the issue the same loss of pressure occurred.

By "loss of pressure" I infer there was still some flow, albeit reduced. This would not happen if the thermal overload tripped. More likely the water level drew down to either go off the curve or suck in air.

 

[George G]

@LLigetfa That's correct, water did not simply stop abruptly like when the electricity supply is stopped. It was still pumping but with much reduced pressure.

@LLigetfa, are you also of the opinion that the pump is probably fine?

 

[Reach4]

A 3/4 hp 5 gpm pump is enough pump. It has more stages, and it can raise water higher.

A 3/4 hp 7 gpm pump is maybe enough pump, and that could explain your symptom-- as the water level approached 300 ft down, the flow rate would reduce. That is not all bad when you contrast that with sucking air.

A 3/4 hp 10 gpm pump is not enough pump to produce pressure for running a garden hose nozel sprayer , and that could explain your symptom-- as the water level approached 300 ft down, the flow would reduce considerably. That is not all bad when you contrast that with the alternative of sucking air.

 

[Valveman]

I was guessing it is a 5 GPM, 3/4HP. That can be confirmed by seeing how much it pumps when the water level is high and the pipe or valve is wide open. You will get 7-8 GPM max with a 5 GPM pump, 11-12 GPM max if it is a 7 GPM pump. The 5 GPM pump will still pump 6 GPM from 300' deep.

Still need to check the amps. Pumping the well dry will cause the amps to drop off from normal amps fast the same as the water coming out. Low amps and low flow to start with is a worn pump or something restricted. High amps will trip the overload in the motor, and the pump won't run until it cools down and re-sets. The first one means your pump is fine, the other two means there is a problem.

 

[George G]

A 3/4 hp 5 gpm pump is enough pump. It has more stages, and it can raise water higher.

A 3/4 hp 7 gpm pump is maybe enough pump, and that could explain your symptom-- as the water level approached 300 ft down, the flow rate would reduce. That is not all bad when you contrast that with sucking air.

A 3/4 hp 10 gpm pump is not enough pump to produce pressure for running a garden hose nozel sprayer , and that could explain your symptom-- as the water level approached 300 ft down, the flow would reduce considerably. That is not all bad when you contrast that with the alternative of sucking air.

I believe the pump is rated 7 GPM.

Specs say "Best Efficiency Flow" 7 GPM
"Flow Range" of 1.5 - 10 GPM

 

[George G]

I was guessing it is a 5 GPM, 3/4HP. That can be confirmed by seeing how much it pumps when the water level is high and the pipe or valve is wide open. You will get 7-8 GPM max with a 5 GPM pump, 11-12 GPM max if it is a 7 GPM pump. The 5 GPM pump will still pump 6 GPM from 300' deep.

Still need to check the amps. Pumping the well dry will cause the amps to drop off from normal amps fast the same as the water coming out. Low amps and low flow to start with is a worn pump or something restricted. High amps will trip the overload in the motor, and the pump won't run until it cools down and re-sets. The first one means your pump is fine, the other two means there is a problem.

Would reducing the hose size as we get further away from the well effect things?

When we first start the pump and let it discharge right at the well head, it runs beautifully. In both instances the problem seems to be effected by the use of garden hose. It's clear that switching the valve to supply the garden hose increases pressure in the supply line quite a bit. My initial concern was: did we increase that pressure (reduce the flow) too much through use of the hose?

 

[Valveman]

I believe the pump is rated 7 GPM.

Specs say "Best Efficiency Flow" 7 GPM
"Flow Range" of 1.5 - 10 GPM

Yep. That is a 7 GPM series. If it is only pumping 5 GPM wide open, it is either pumping from 350' deep, the pump is worn or clogged, or there is a lot of restriction.

If restricting the flow with a valve or extra long hoses causes the amps to increase and trip the overload, the thrust bearing in the motor is bad.

That size pump only needs 2/10s of a GPM flowing to stay cool. As long as the pump is not restricted to less than 1 GPM it will stay cool. However, the flow, especially small flow, needs to go past the motor before going into the pump, or the thrust bearing in the motor will get hot and fail. Restricting or closing a valve on the discharge of the pump is how you test a thrust bearing. Restricting the flow of a pump should cause the amps to decrease. If restriction causes the amps to increase, the thrust bearing has failed.

The only way to make sure the flow goes past the motor before going into the pump is to set the pump above where the water comes into the well, or to use a shroud or flow inducer sleeve on the pump.

 

[George G]

Yep. That is a 7 GPM series. If it is only pumping 5 GPM wide open, it is either pumping from 350' deep, the pump is worn or clogged, or there is a lot of restriction.

If restricting the flow with a valve or extra long hoses causes the amps to increase and trip the overload, the thrust bearing in the motor is bad.

That size pump only needs 2/10s of a GPM flowing to stay cool. As long as the pump is not restricted to less than 1 GPM it will stay cool. However, the flow, especially small flow, needs to go past the motor before going into the pump, or the thrust bearing in the motor will get hot and fail. Restricting or closing a valve on the discharge of the pump is how you test a thrust bearing. Restricting the flow of a pump should cause the amps to decrease. If restriction causes the amps to increase, the thrust bearing has failed.

The only way to make sure the flow goes past the motor before going into the pump is to set the pump above where the water comes into the well, or to use a shroud or flow inducer sleeve on the pump.
View attachment 91852

Fantastic information, thank you so much.

I just checked, and the pump is actually 400' down, not 300'. This, I suppose, would account for the 5 GPM?

If the thrust bearing did fail, would one expect this to be consistently symptomatic (even when well is run full open) or would it be intermittent and more prone to exhibiting symptoms when in a reduced flow state?

 

[George G]

btw, @Valveman , I plan to check it with a basic clip around amp meter. Can you describe the appropriate tests I should perform to assess?

I understand the thrust bearing test above. What else would help me to test the health of my pump? Running the well dry has not always been a possibility, as sometimes the well produces more water than the pump can expel. However, this obviously may not be the case right now...

 

[Valveman]

if the water level is at 350', 5 GPM is all that pump can do. How much flow you are using, as long as it is more than 1 GPM, is not going to affect the thrust bearing. It is where the pump is installed in the well. With the pump set at 400', if the water coming into the well is coming in at 390' or higher, the water is not going past the motor before it goes into the pump.

With a shroud or flow inducer sleeve water will flow past the motor no matter where it comes into the well. But without a flow inducer sleeve the pump needs to be set above the incoming water. The motor is below the pump intake and the water must come to the pump from below to cool the motor.

 

[Valveman]

btw, @Valveman , I plan to check it with a basic clip around amp meter. Can you describe the appropriate tests I should perform to assess?

I understand the thrust bearing test above. What else would help me to test the health of my pump? Running the well dry has not always been a possibility, as sometimes the well produces more water than the pump can expel. However, this obviously may not be the case right now...

Clip the amp meter around one of the hot wires at the breaker, pressure switch, or control box. When the pump starts and there is plenty of water in the well a 3/4HP should draw about 7 amps. As the water level drops in the well the amps will decrease and probably drop to about 5-6 amps when pumping 5 GPM. But if you pump the well dry you will see the amps drop suddenly from 5-7 amps to 2-3 amps. That means your pumping the well dry. If the amps start out low and you are sure there is plenty of water in the well, the pump could be worn or the screen clogged. If the amps ever go above 7 amps, the overload should trip and turn off the motor, showing zero amps. If starting the pump causes high amps and trips the overload, the start capacitor in the motor or control box is bad.

 

[George G]

Thank you so very much. I'll let you know what we learn.

 

[George G]

if the water level is at 350', 5 GPM is all that pump can do. How much flow you are using, as long as it is more than 1 GPM, is not going to affect the thrust bearing. It is where the pump is installed in the well. With the pump set at 400', if the water coming into the well is coming in at 390' or higher, the water is not going past the motor before it goes into the pump.

With a shroud or flow inducer sleeve water will flow past the motor no matter where it comes into the well. But without a flow inducer sleeve the pump needs to be set above the incoming water. The motor is below the pump intake and the water must come to the pump from below to cool the motor.

So, in other words, even if the pump is submerged in water, if the water is entering above the pump, that water is not passing by the motor, and therefore the water under the pump progressively gets warmer and warmer?

 

[Reach4]

Goulds has more than one 7 gpm 3/4 hp pump. This is one, but typical.
Note that with the 7GS07, as the depth to water increases, the gpm drops. For example, if the water falls to 340 ft, and the flow is 1.8 gpm, then that develops about 20 psi. You would notice that your sprinkler puts out less.

For watering with a sprinkler, you might want to let the water level recover after irrigating for a while.

 

[Valveman]

Normally we run it to fill a 1000 gallon tank and then have a second pump satisfy our garden needs.

I was not figuring any pressure when I said it would do 5 GPM at 350', which is what the curve says. I don't know if Goulds has more than one 7 GPM, 3/4HP, but even that one was changed a few years ago. I am using the newer versions curves which show the GS series pumps building considerably more head than the older curves. Using the older curves got me in trouble a time or two before I figured it out.

 

[Valveman]

So, in other words, even if the pump is submerged in water, if the water is entering above the pump, that water is not passing by the motor, and therefore the water under the pump progressively gets warmer and warmer?

Yes.

Pump Sleeves help direct water flow to properly cool motors.
Submersible pump motors require water flow over them to dissipate heat. In open water, such as a lake or cistern or in large diameter wells, heat dissipation becomes a problem since water is likely to flow directly into the intake of the pump, instead of flowing over the motor. In these situations, a pump sleeve or shroud is required. Pump sleeves are also required if the well is top feeding (water flows in from above), or if the pump is placed below screens or perforations, and sand is able to fall into the pump inlet. As a side note: pump sleeves, flow sleeve, flow inducer sleeve, and pump shroud all mean the same thing!

A PumpSleeve / FlowSleeve is simply a PVC pipe that prevents water flow into the pump from the lateral directions, and directs waterflow to enter from the motor's end, allowing for water to pass over the motor first before entering the intake.

 

[Fitter30]

You have a the pump set measurement what about how deep is the well and top level.