How to Recover a Lost Submersible Well Pump

[turnkey4099]

Sorry I missed that. It is unusual to have that many storage tanks ganged together, but I can see where it might be much less expensive than one huge tank. No matter if it is one big tank or a gang of small tanks there needs to be enough water in the storage tank(s) as needed. It is not like a well with an unlimited supply of water. When pumping from storage tanks or a well a pressure tanks only purpose is to limit the on/off cycles of the pump. The water comes from the well and/or storage tanks, not the pressure tank. So, the pressure tank can be very small if you have some other way to limit the cycling like a Cycle Stop Valve. Even with multiple pumps of varying sizes the pumps will either cycle off and on no matter how large the pressure tank, or can be made to deliver constant pressure without cycling the same way.

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"...
When pumping from storage tanks or a well a pressure tanks only purpose is to limit the on/off cycles of the pump. The water comes from the well and/or storage tanks, not the pressure tank. ..."

Wrong...at least with a standard, not cycle stop valve. Pump runs until the cut-off pressure is reached. Any water drawn until cut-in pressure is reached is coming out of the tank.

 

[Valveman]

A pump delivers water straight from a well or a storage tank to the taps. A pressure tanks only purpose is to store the excess water that the pump makes over what is being used. Then, as you said, the pump runs until the cut-off pressure is reached. At that point, water that "came from the well", is drawn from the pressure tank for a short time, to limit the on/off cycles of the pump.

When using a CSV or a VFD the output of the pump is changed to match the amount being used. Cut-off pressure is never reached while a tap is on. Water is going right past the pressure tank as if it wasn't even there. Water is coming from the source and a pressure tank isn't really needed at that point.

Water can also be supplied straight from the well without a CSV or VFD, but without a pressure tank the pump will just cycle on and off rapidly to supply what is needed.

The point is... A lot of people see a big 80 gallon pressure tank and think they have lots of water. In reality an 80 gallon pressure tank only holds 20 gallons of water. And that is when it has been filled with a pump from a real source of water, which is your well, cistern, or other supply. Having a huge pressure tank doesn't mean you have a good water supply.

 

[Valveman]

I have another well with the pressure tank and standard setup. It doesn't negate the freq drive at all. The freq drive soft starts the pump and only runs it fast enough to maintain the 50 lb pressure. It uses 3 wires to basically turn the pump into variable speed. Even though I am in love with it the price is a factor. I will not likely put one on my second well because I can pull it by hand and change the pump in about an hour.

Yeah, VFD's are great as long as you can afford to keep them working. If it is a Subdirve and you start having problems you are stuck replacing the expensive controller. if it is a Monodrive with a single phase motor you can replace the VFD with a Cycle Stop Valve. If your second well is single phase all you need is to add a Cycle Stop Valve. You will love the constant pressure from the CSV even better than from a VFD.

 

[3Ts]

... Then, as you said, the pump runs until the cut-off pressure is reached. At that point, water that "came from the well", is drawn from the pressure tank for a short time, to limit the on/off cycles of the pump.

When using a CSV or a VFD the output of the pump is changed to match the amount being used. Cut-off pressure is never reached while a tap is on. Water is going right past the pressure tank as if it wasn't even there. Water is coming from the source and a pressure tank isn't really needed at that point. ...

The well pump that I have depends on the water flow over it for cooling and needs to run for several minutes to keep from overheating. It sounds to me like a low water flow would cause the pump motor to overheat.

 

[aczlan]

The well pump that I have depends on the water flow over it for cooling and needs to run for several minutes to keep from overheating. It sounds to me like a low water flow would cause the pump motor to overheat.

That is one thing that properly setup VFDs will have a limit for, they will have a minimum speed setpoint.
On a CSV, the CSV doesn't change the pump output so much as the well output, it's a pressure relief valve that is set to a lower pressure than the shutoff pressure and when it opens up, it dumps flow in excess of what is allowed back into the well.

So (picking random numbers), if your well is set to turn on at 30PSI, off at 50PSI and flows 10GPM.
The CSV could be set to open at (picking a number) 45 PSI, but it maxes out at 8GPM, so you can flow 2.2GPM all day, the pump is moving 10GPM, the CSV flows 7.8GPM and it keeps running all day.
Once you shut the water off, the CSV flows the full 8GPM until it reaches 50PSI and then the pressure switch shuts it off.
Not sure if it also has a check valve to keep your system at 50PSI until you open the valve, or if it drains back down to 45PSI.

Aaron Z

 

[Valveman]

The well pump that I have depends on the water flow over it for cooling and needs to run for several minutes to keep from overheating. It sounds to me like a low water flow would cause the pump motor to overheat.

You are correct that water flow over the motor is what keeps it cool. And when running at full load amperage a motor needs to run for AT LEAST one minute, two minutes is better, to dissipate the heat caused by start up. Then the motor needs to remain off for AT LEAST a minute, two is better, to cool off before it restarts.

0.5 feet per second or 0.25 fps flow over the motor is needed to keep it cool when running at full load amps. However, when using a Cycle Stop Valve the motor amps decrease from 10% to 60%. With reduced amperage the motor is de-rated and doesn't require as much flow or for as long. When the amps are reduced because the CSV has restricted the pumps output to 1 GPM, the motor no longer needs 0.25 fps for a minute to cool off. The CSV also prevents the pump from shutting off as long as you are using more than 1 GPM, so it doesn't go off until you stop using water, and needing a minute or two to cool down is a moot point.

Without a CSV you need at least one minute on and one minute off. With a CSV the 0.25 fps for at least a minute is not applicable. With a CSV the pump will run at reduced amperage as long as you are using water and only requires about 2/10s of a GPM flow to remain cool. The 1 GPM minimum built into the CSV is actually 5 times more flow than the 2/10s of a GPM needed to keep the motor cool.

 

[Valveman]

That is one thing that properly setup VFDs will have a limit for, they will have a minimum speed setpoint.
On a CSV, the CSV doesn't change the pump output so much as the well output, it's a pressure relief valve that is set to a lower pressure than the shutoff pressure and when it opens up, it dumps flow in excess of what is allowed back into the well.

So (picking random numbers), if your well is set to turn on at 30PSI, off at 50PSI and flows 10GPM.
The CSV could be set to open at (picking a number) 45 PSI, but it maxes out at 8GPM, so you can flow 2.2GPM all day, the pump is moving 10GPM, the CSV flows 7.8GPM and it keeps running all day.
Once you shut the water off, the CSV flows the full 8GPM until it reaches 50PSI and then the pressure switch shuts it off.
Not sure if it also has a check valve to keep your system at 50PSI until you open the valve, or if it drains back down to 45PSI.

Aaron Z

Well no! That is not how a CSV works. The CSV is not a pressure relief valve. It does not dump excess water. The CSV works like a pressure reducing valve and restricts the flow from the pump to match the amount being used down to 1 GPM. If you are pumping 2.2 GPM all day, the CSV makes the pump put out exactly 2.2 GPM all day. Restricting the flow from the pump reduces the amp draw and makes the motor run cooler. The reduced amperage will allow the pump/motor to work safely down to as little as 1 GPM. There is no extra water produced to pop off like with a pressure relief valve when using a CSV.

Yes, A CSV system still needs a normal check valve to keep the pump from coming back on until you use some water.

And yes, a VFD should have a minimum speed or flow programmed in to prevent overheating of the pump/motor. But when a VFD reduces the amp draw of a motor, it is creating a smaller motor from a large one, not de-rating the motor load like a CSV does. When a VFD reduces the amp draw, the motor must still have the 0.25 fps flow to remain cool, the same as a smaller motor would require. In other words, a CSV will let a motor run safely at much lower flow rate than a VFD.

 

[Flogger]

I would advise talking to a few well drillers and water engineers before choosing a csv. If my well was shallow enough to manage a pump change myself I might consider it. My guide in my deepwell adventure has been making a living as a troubleshooter for years. He warned me away from them. As the drillers crew was installing my wellhouse they said A ground rod was a waste because he had seen a demonstration that showed it took 20 of them to trip a 20 amp breaker. He obviously missed a few demonstrations so after they left I drove the ground rod as needed and grounded my lightning arrestor just like it should be. My point is you have to know when you are dealing with knowledge and when your not. I have experienced zero problems with my sub drive. If I do you can bet I'll analyze my setup and correct any shortcomings on my part before repairing the problem.

 

[Valveman]

When well drillers and water engineers have problems they can't solve, they call me for advice. Lol! Your "guide to your deep well adventure" warned you away from a CSV because he wanted to sell you a Subdrive, as he makes a lot more money that way. He was as wrong about that as he was about not needing a grounding rod. You do have to know when you are dealing with someone knowledgeable and when you are not. And the ground rod issue should have given you a clue. Except for the cost, Subdrives are great as long as they are running because they produce constant pressure similar to a Cycle Stop Valve. But they normally do not stay working for very long. The warranty was changed from 5 to 3 years for that very reason. Repairing the problem will mean either continue replacing the expensive Subdrive or find an alternate solution like the Cycle Stop Valve that will last. If you have gotten use to replacing expensive appliances every 5 years or so, you will love your Subdrive. But yeah, that constant pressure is nice isn't it?

 

[Flogger]

When well drillers and water engineers have problems they can't solve, they call me for advice. Lol! Your "guide to your deep well adventure" warned you away from a CSV because he wanted to sell you a Subdrive, as he makes a lot more money that way. He was as wrong about that as he was about not needing a grounding rod. You do have to know when you are dealing with someone knowledgeable and when you are not. And the ground rod issue should have given you a clue. Except for the cost, Subdrives are great as long as they are running because they produce constant pressure similar to a Cycle Stop Valve. But they normally do not stay working for very long. The warranty was changed from 5 to 3 years for that very reason. Repairing the problem will mean either continue replacing the expensive Subdrive or find an alternate solution like the Cycle Stop Valve that will last. If you have gotten use to replacing expensive appliances every 5 years or so, you will love your Subdrive. But yeah, that constant pressure is nice isn't it?

Physics class tells me different. I would not toss the Dole, csv type valve out of the equation but I wanted the soft start feature plus if lightning sends my freq drive blasting out of the well house in flames there is still a chance the pump could survive. My guidance counselor sold me nothing but a lot of amicable phone time I do not believe the principles of operation of a dole/csv valve would not increase run time and head on my pump. As far as freq drives I drink beer with a neighbor that makes 6 figures telling people how to make them work. Those two and my many years as an AT&T power man gives a touch of insight.