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SwedishRider
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[Plumbing] Well Pump Upthrust issue: Dole Restrictor Valves good or bad?

Since my new well pump and tank, I've been doing some observing and calculating. Here's the setup:

Goulds 5GS05412C pump(stainless steel): »www.aquascience.net/submersible-···m?id=362

Amtrol WX-202 tank: »www.aquascience.net/amtrol-press···m?id=502

Well is about 260' deep with static water 30' below the surface of the ground, and the well is somewhat uphill from the house. Recovery rate is about 8 GPM. Tank pressure switch is set to 40psi/60psi.

I watched the tank cut in at 40psi, and then cut out at 60psi, and to fill the tank's volume of 5.9 gallons was about 26-27 seconds. Obviously too short of a run time. However... let's think about that. If 5.9 gallons was pumped in 26-27 seconds, that means that the pump is pumping about 13 GPM! ((5.9/27)*60)=~13 GPM. The pump is supposed to pump 5 GPM, but has a range of 1.5-7.5 GPM.

After some research, it appears my well's static high water table (and positioning of the well a bit uphill of the house) has created upthrust in the pump, making it capable of pumping more than it's max rated capacity.

So, I looked for a solution, and Gould's recommends use of a Dole Restrictor Valve to limit the maximum flow of the pump: »www.aquascience.net/template/pro···&catid=1

It would be placed right before my pressure tank, and would create backpressure on the water lines to give the pump something to pump against, thus ending the upthrust issue. Honestly... this sounds awfully close to the cycle stop valve concept we've been kicking around here for some time.

So.... the questions....

Is upthrust a big enough deal to want to put that much backpressure on all my well piping to satisfy the pump? Some argue that it's a non-issue, and others say upthrust will send the pump into retirement very early in its life. Does upthrust really matter in a typical home installation?

Is it worth the risk of the backpressure that would be created all the way back to the well? There seems to be two schools of thought... one being let the pump alone and keep pressure at 40/60 and try to get a well run time of about a minute as best you can, regardless of GPM over the pump's rated GPM. The other is to use the Dole Valve to control the pump's output, and that the backpressure created won't be an issue.

I think a larger tank is obviously on the menu for my system... but should a Dole restriction valve be on the radar as well?!?

LittleBill

join:2013-05-24
kudos:1
can you get a 5 or 6 gpm restrictor? that would eliminate the need for a new tank

golds would honestly have to answer you on this. the only thing i can think is when pumping, it may over speed the pump, but it can also be similar to just pumping at a very shallow depth

if golds is saying put in the restrictor, i would simply for warranty concerns

garys_2k
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Farmington, MI
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·Callcentric
reply to SwedishRider
said by SwedishRider:

...Gould's recommends use of a Dole Restrictor Valve to limit the maximum flow of the pump

Take their advice, they should know what is needed. Adding the backpressure would be the same as having a lower static water level in your well, IOW it's fine and normal.


Jack_in_VA
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North, VA
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reply to LittleBill
said by LittleBill:

can you get a 5 or 6 gpm restrictor? that would eliminate the need for a new tank

golds would honestly have to answer you on this. the only thing i can think is when pumping, it may over speed the pump, but it can also be similar to just pumping at a very shallow depth

if golds is saying put in the restrictor, i would simply for warranty concerns

The pump cannot be over-sped. The motor speed is determined by the number of poles and the frequency.


SwedishRider
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reply to garys_2k
What no one seems to be able to tell me is how much back pressure will be created in the piping from the dole valve back to the pump. A method on how to calculate it would be best actually. I don't mind putting one on there if there is no risk of excessively high pressure in those lines. It really is very similar to going with a CSV.

The last thing I need is to create enough back pressure to rupture a line underground or in the well.


Jack_in_VA
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reply to SwedishRider
said by SwedishRider:

So, I looked for a solution, and Gould's recommends use of a Dole Restrictor Valve to limit the maximum flow of the pump: »www.aquascience.net/template/pro···&catid=1

Take their advice but your issue raises a question. It appears you got less than a quality install from your installer who should have checked this out and corrected it before declaring the job complete. It should not fall to you to correct it on your own.


SwedishRider
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I want to put blame aside for the moment and figure out the correct path to take given the scenario.

What of upthrust Jack? Is it a nonissue in the grand scheme or is it worth fooling with system back pressure? I know you are not a fan of CSVs, and a Dole valve seems to do a very similar job.


Jack_in_VA
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Like I suggested go with the Gould Pump recommendation. That should satisfy any warranty problems should they occur vs the possible problem if a csv is on the system. You would not be regulating pressure very long with a csv so really would do no good.

I don't think the upthrust is a problem but the quick start and stop definitely might shorten the life of the pump motor. Consider also a much larger pressure tank since you have such a good flow rate from the pump.

robbin
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join:2000-09-21
Leander, TX
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reply to SwedishRider
Do you know the depth that your pump is set at?


SwedishRider
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I think it's about 10 to 20 feet off the bottom (which is 260').


SwedishRider
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1 edit
reply to Jack_in_VA
I agree and disagree with you Jack. To do right by the pump, theoretically the dole valve is the way to go. But... as much as a pump failure would suck, a blown line in the house or underground would suck much, much more. Without knowing for sure, I would err on the side of protecting the lines over the pump. And that assumes upthrust would actually result in a problem. The last pump in there had a check valve failure after four years... And it was 3/4 hp with even more capacity than the Goulds in there now!! I can't say upthrust was an issue that I ever dealt with, making me wonder how much of an issue upthrust really is on a residential well.

robbin
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Leander, TX
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I would run a better test of the flow you are getting. Looking at the pump specs, it is speced to pump it's max of 7.6 gallons per minute at 50' water depth. So, in essence, you just have 20' too much water which is about 14 gallons and less than 10 psi of water column. That doesn't sound like enough difference to create the flow you seem to have measured. I don't think there is a problem with upthrust if it only happens at start up. The problem is going to occur if your system always has upthrust. If this is mainly a start up problem, then a larger storage tank may solve the problem. If you want to experiment then put a pressure gauge and valve before the check valve (gauge on well side). Then you can experiment with flow restriction and how it effects pressure on the well plumbing.


SwedishRider
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Robbin, my last pump failed at a bit over four years due to the check valve failing, nothing to do with a motor or pump failure. Since the check valve was built into that pump, it was junked in favor of this Goulds stainless steel unit. The construction on this pump is much more rugged than the last pump as well (last one was composite plastic). Upthrust was not an issue as far as I can tell.

I am making some assumptions with my calculations using my tank's specs as the baseline. Numbers may be off, but 26 seconds is clearly too short of a run time. If the pump actually pumped at 5 GPM, the tank would be sized properly, but my high static water level threw those numbers way off.


Msradell
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Louisville, KY

1 edit
reply to SwedishRider
Have you looked at the option of installing a larger tank? That would allow you to keep the same flow rate out of the pump but the pump would run longer before it reached the shut off point. This solution would have the advantage of not putting additional pressure on the system as well if allowing you to have the full higher flow rate available if needed.

Something like this tank »www.aquascience.net/amtrol-press···?id=1365 he view approximately 1 minute runtime. An additional benefit would be that your pump would not have to cycle as often when you are using water

Written using Dragon NaturallySpeaking


SwedishRider
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Tank is 20 gallons, with a 40/60 drawdown of 5.9 gallons. A larger tank would maximize pump runtime, but would not address the issue of upthrust (if it's even an issue worth considering).


Msradell
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I've never seen any data showing that upthrust is a bad thing. Maybe Goulds could give you more information about that. To me the bigger issue is the short cycle time of the pump.
--
Written using Dragon NaturallySpeaking


SwedishRider
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I'll try to more accurately test the water flow. I am looking at the WX-203 as the replacement tank. The 40/60 drawdown is 9.6 gallons, so if the GPM ends up being about 10 GPM, that would be my choice. The T from my WX-202 would simply bolt up (anything bigger than the 203 would require a new T), and it would fit in exactly the same space, only taller.


Jack_in_VA
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reply to Msradell
said by Msradell:

I've never seen any data showing that upthrust is a bad thing. Maybe Goulds could give you more information about that. To me the bigger issue is the short cycle time of the pump.

I lived in a house 10 years with a 1 hp submersible pump in a 30 ft shallow well so you can imagine the upthrust on it. It would run 2 sprinklers on 3/4" hoses and cut on and off. (and no I never ran the well dry). That provided a wonderful car wash water supply

The original pressure tank was about 5 gal mounted between the floor joists in the unfinished basement. When I finished the basement I removed it and installed a 80 gallon tank in my new utility room.

robbin
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Leander, TX
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reply to SwedishRider
said by SwedishRider:

A larger tank would maximize pump runtime, but would not address the issue of upthrust (if it's even an issue worth considering).

There you are making an assumption that the upthrust is constantly occurring whenever the pump is running. I am suggesting that once the pump starts and draws the well down, it may no longer be an issue. That is why I would like to see a more detailed flow test. Personally I don't like to see a pressure tank sized so closely to actual well performance. I like to see my pump run for minutes or longer.


SwedishRider
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I'm not even sure if upthrust is really a problem in the first place. The only thing I am sure of is that the cycle time is too short. I think the minute or so run time is acceptable, at least for my purposes.

Again, my last pump must have cycled even quicker than this one, and it failed a check valve death, not a motor or pump death. Given it was composite plastic, and this one is stainless, I think about a minute runtime should work acceptably.

robbin
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Leander, TX
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Have you double checked that the installers set your pressure tank to the correct pressure?


SwedishRider
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Yes, it's at 38psi with a cut-in of 40psi.


Raphion

join:2000-10-14
Samsara
Reviews:
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reply to SwedishRider
I think the issue with lower load on that type of pump is probably that when it's outlet pressure is low, the water flows through the impeller faster than it's designed for. When that happens, gasses dissolved in the water pop out of solution explosively due to vacuum developed along the impeller's surfaces, and the little bubbles exploding up all around the impeller do damage to it, gradually abrading the material away, no matter what it's made of, since it's a mechanical assault rather than a chemical one. Raise the outlet pressure with a restrictor, and the velocity comes down, and reduce the cavitation and associated damage.

Short cycle time can be very harmful, because the startup puts the most stress on the motor and bearings. You want to keep the cycling to the minimum you can practically achieve. While the restrictor valves would lengthen the cycle time a bit, I would still want to replace the tiny pressure tank with a much MUCH larger one, and, optionally, add a pressure regulator after the tank, set to the pump's cut-in pressure, so your house water pressure doesn't rise and fall with the cycles.


StillLearn
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join:2002-03-21
Streamwood, IL
reply to SwedishRider
Did an applications person at Goulds tell you that you should use a Dole valve, or did you find some literature that caused you to think that? If it is literature, do you have a link?


SwedishRider
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Instruction manual, page 12: »www.aquascience.net/resource/lit···nual.pdf


SwedishRider
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reply to SwedishRider
Does a submersible pump throttle itself down when a Dole flow restrictor or a CSV is introduced? I keep getting the impression that as back pressure increases, the pump "ramps down", and draws less energy while producing less GPM.

Am I thinking of this correctly?

robbin
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Leander, TX
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The way I understand it the pump is designed to work with a certain amount of head pressure. If the pressure is lower than design then the pump runs faster than design. When it does this the amperage usage increases by a large factor. I don't think you get any efficiency by slowing it down once you get the pump operating in it's curve. If anything, slowing it down at that point could also decrease efficiency as the decrease in flow is not linear with decrease in energy usage.


SwedishRider
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Interesting. I also read that before using a Dole restrictor valve, make sure your piping can withstand the pressure generated from the valve.

Some precaution should be taken to assure that line pressures before the valve do not exceed the capacity of the plumbing lines (since pumps will often produce higher head pressures when throttled back).

»www.wellpumpsandfilters.com/DOLE···519.html

But I can't find anywhere that I can make that calculation. I think I'm going to lean away from any CSV or Dole valve and look to increase my tank size to get about a minute or so in cycle time.

I just have too many unanswered questions about the pressure in those lines in the well and underground.


pende_tim
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Andover, NJ
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reply to SwedishRider
Have you put an Amprobe on the motor to compare rated amps to actual?

Another test I would do is to fill the tank until the pump kicked off and then drain down into a bucket until until the pump is ready to kick on to actually measure the gallons that are being delivered in those 26 seconds.

From the charts on the link, I am having trouble seeing how you are getting almost 2x the flow out of that pump. For example, when the tank pressure builds to 50PSI with a 20' well depth, the flow drops to 7.6 GPM. So you are pumping at 7 GPM for the last 50% of the fill. This means that you must be pumping at 20 GPM or so initially to average 13 GPM overall.

Also looking at the chart at 40PSI tank, changing the water depth from 100 to 60' only increases the flow by 0.5 GPM. Granted the changes are not linear, but dropping to 20' well (30' static - the down hill elevation change ) and ending up at over 13 GPM does not seem realistic.

I would call the well guy and ask him if he has any ideas.

You may not need a Dole. The pump manual suggests pumping into a bucket and using a ball valve to throttle.

Tim
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The difference between genius and stupidity is that genius has its limits.


Raphion

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Samsara
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2 recommendations

I think the calculation is based on a false premise, namely that the pressure tank is empty when the pump cuts in. It should never be empty, so it did not pump 5.9 gallons in 27 seconds, rather, it pumped enough back into the tank to bring the pressure back up to 60psi. It should be neither completely full at cut-off, nor completely empty at cut-in.

It may not be running too fast at all, but the pressure tank is simply too small.