1 ¼ Inch Sch. 120 PVC for 3 HP Pump

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Toukow

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Can you guys help me out on drop pipe pump HP capacity? I currently have what seems to be a stout setup of 180 ft well, water at 170 ft. 1 ¼ inch galvanized rigid steel down pipe, 3 HP Gould 33GS30 pump. If this pump appears oversized, it is. This is due to the local county code that my house be equipped with a sprinkler system. To avoid having to have a 1000 gallon holding tank, a well pump which could deliver over X gallons per hour removed this requirement.


I have received a quote which is calling out the use of 1 ¼ inch Schedule 120 PVC with stainless steel fittings.


My question is straightforward. When I watch the video at the link from RC Worst, or examine the information at the other link, the 3 HP pump appears to exceed the rating for the 1 ¼ inch Sched 120 PVC. Am I just misunderstanding the information presented? Is 1 ¼ inch Sched 120 PVC totally adequate for this application? Thanks, Toukow





https://www.slpipe.com/product/drop-pipe/
 

VAWellDriller

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Can you guys help me out on drop pipe pump HP capacity? I currently have what seems to be a stout setup of 180 ft well, water at 170 ft. 1 ¼ inch galvanized rigid steel down pipe, 3 HP Gould 33GS30 pump. If this pump appears oversized, it is. This is due to the local county code that my house be equipped with a sprinkler system. To avoid having to have a 1000 gallon holding tank, a well pump which could deliver over X gallons per hour removed this requirement.


I have received a quote which is calling out the use of 1 ¼ inch Schedule 120 PVC with stainless steel fittings.


My question is straightforward. When I watch the video at the link from RC Worst, or examine the information at the other link, the 3 HP pump appears to exceed the rating for the 1 ¼ inch Sched 120 PVC. Am I just misunderstanding the information presented? Is 1 ¼ inch Sched 120 PVC totally adequate for this application? Thanks, Toukow





https://www.slpipe.com/product/drop-pipe/

I know SCH 120 Johnson Screens Shur Align pipe says 2HP max for 1 1/4". I'm not sure about the threaded both ends with stainless couplings, but I would think its not really appropriate. SCH 120 PVC is very heavy sidewall (small ID)...1 1/4" has terrible headloss at the flow rates that pump will produce....so you should definitely push for steel and maybe want to bump to 1.5". You have a 180' well and water is at 170'??? Did you mean to say you have 170' of water in the well? Will the well yield keep up with that pump?
 

shane21

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Before getting to the technical info below, I agree w/ VAWellDriller that you need to clarify the specs on the well of a 180' deep with water at 170'. My experience has been that while that is possible, it isn't very common you find a well with a 10" standing head of water that is capable of producing 25+ GPM flow rates.

If all the information you posted is indeed correct, and assuming you will have a system operating at 60 PSI, the technical info below will give you a pretty good idea of what the quoted system will provide and why it is a poorly designed system. If you made a mistake with the info you provided, like the depth to water measurement, then all the information below won't be accurate.

As VAWellDriller stated, 1-1/4" SCHD 120 PVC provides a terribly undersized inner diameter (ID) pipe for your situation. Just a quick calculation using friction loss tables shows your setup would only yield ~18.5 gallons per minute (GPM) @ 60 PSI if taken directly from the top of the well casing. That doesn't even account for the additional fiction loss you will encounter with the rest of the plumbing from the well to house, at the tank tee and the rest of the house plumbing. For reference, an 18GS20 in your situation would yield~17 gallons per minute (GPM) @ 60 PSI if taken directly from the top of the well casing - an 8% reduction in performance for a pump/motor that will be probably $500-$700 cheaper to buy and use ~28% less energy than the 3HP motor you were quoted.

Installing the 33GS30 on SCHD 120 1-1/2" would get you ~21 GPM while jumping to SCHD 80 2" would get you to ~25 GPM. I suggest you find out what GPM or gallons per hour (GPH) rate of flow your local code is requiring to make sure your system can provide it. Then I would suggest you find out why someone is specifying such undersized drop pipe for that well pump.
 

Toukow

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My apologies for being inaccurate with the initial information I provided. And Shane21 I appreciate you doing the numbers with my bogus data, again sorry about that. I found the well report and it says ' Depth of completed well 186 ft' and 'WATER LEVELS: Static level 105 ft below top of well'. I do not see a statement of actual installed pump elevation in the report, but the bill stated '179 Ft 1 1/4" galvanized pipe'. The report does state 'airtest 30-35 gallon/min with stem set at 183 ft for 1 hour'. The 30 gallons sticks in my mind as required to remove the county requirement of a large sprinkler reservoir (neighbor's is around 900 gallons), but can research.

In defense of the current installer's proposal, I said to 'replace everything' with the same materials given the system's longevity. This appeared very good after reading forum member's comments in this regard of pumps lasting 5-7 years, which I find ridiculous. If this is a poorly designed system as proposed, pending the accurate data provided above, that's on me.

I started this question simply asking about the down pipe sizing being specified , but here's the whole deal.

The Gould pump is not meeting the manufacturer's requirement of 2 minutes per run. It only runs almost exactly 1 minute. It is feeding (2) Wellmate 85 gallon tanks, with bladders functioning. My existing pump turns on at tank pressure of 36 PSI, and off at 60 PSI.

I initially was tempted to downsize the pump HP to meet the run time requirement, but worry about the fire sprinkler legalities in this regard. And on the other hand, the Gould 3 HP has lasted 15 years, so maybe I should simply ignore the 2 minute per run requirement of the manufacturer? Most of the life of the pump has supported a household of two people and we didn't stress the system whatsoever. A few years ago I installed a drip watering system, so the stress on the system has gone up a bit.

The installer wants me to install a VFD pump drive, but I'd like to avoid the complexity if at all possible. That said, this appears to be a good application for such a drive in order to meet the water delivery requirement of the fire sprinkler system, yet respect the manufacturer's minimum run time requirement.

Given I nixed the VFD initially, the quote came back with larger tanks, new control panel, pump, etc. at just around $10,000 with taxes. Hence I'm reevaluating my options, and very glad I'm doing this proactively so have time to review options.

Thanks for your time, and your comments appreciated- Toukow
 

Valveman

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This is one of those applications where simply adding a Cycle Stop Valve will solve the run time problem, and several others you may not even know you have. The CSV12550-3 would hold 50 PSI while you use anything between 3 GPM and 38 GPM. When you close all the faucets it will top off the tank(s) at 3 GPM, allowing you to adjust the run time anyway you want.

 

Boycedrilling

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Your system requirements are the ideal system for a Cycle Stop Valve. You would only need one pressure tank then. It will also be much less expensive than a VFD.
 

Valveman

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Thanks Boyce. But you can still use both tanks if you want. Two 80 gallon tanks should hold about 40 gallons of water combined. When using a 40/60 switch a 5o PSI CSV125-3 will top off the tanks at 3 GPM when above 50 PSI. So, to put the last 20 gallons in the tanks at 3 GPM would take about 7 minutes. If you reduce the pressure switch setting to 35/55, it would take 3.5 minutes to fill the tanks. A pressure switch setting of about 33/53 would give you the two minutes run time you want. With 40 gallons of draw down in the tanks you can adjust the pressure switch to make the CSV fill the tank(s) in as little as one minute or as much as 14 minutes. But with a CSV the run time isn't as important as without, because the CSV will not let the pump shut off until you are finished using water.
 

shane21

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With the revised well characteristic numbers the 33GS30 will produce more GPM but the 1-1/4" drop pipe is still a very poor fit for that pump. I still recommend you find out the minimum required GPM flow to satisfy your sprinkler system before you actively look for pump system prices. It may be the 33GS30 is a perfect fit for your system, including the sprinkler system needs, or it may be that is is too small or too large but why guess when these figures can be nailed down and the proper pump can be sized.

As for the CSV or VFD argument, be mindful of the motor manufacturer's minimum cooling requirements. I know Franklin Electric, an industry standard submersible motor manufacturer, requires a minimum 7 GPM of water flow in a 5" diameter well for a 3 HP motor and even more in a larger diameter well. The 3 GPM flow rate for the Cycle Ctop Valve that valveman recommended would not be adequate if you were using a Franklin Electric motor and you would want to verify the programming on any VFD you install would also provide the proper minimum flow rate required to cool the motor. Different motor manufacturers may or may not minimum flow requirements, just be sure you check into that and your pump installer designs the system correctly if you use a CSV or VFD.
 

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Actually 3 GPM is more than needed to cool a 3HP Franklin motor, as long as it is running on standard AC current and the amps drop by at least 10%, like when using a CSV. As per Franklin, de-rating a motor by 11% will allow it to safely pump water as hot as 131F degrees. What they don't tell you is that de-rating the motor load will also allow a lower flow rate of cool water than normal. A VFD "creates" a smaller motor from a larger one. Because of the fast switching rate and harmonic content of the power from a VFD that motor needs the same cooling flow as if it were still fully loaded. However, a CSV de-rates the motor load, making it draw lower amps using standard AC power without any fast switching or harmonic content. In this way a CSV can let a motor work safely at a much lower flow rate than a VFD.

Hitachi motors are better than Franklin, but they have the same cooling requirements. I have a couple of letters from Hitachi explaining the de-rating and stating that the motors in question will even work with no flow past them with the amount they are de-rated. It takes very little cooling flow when the amps are reduced, de-rating the motor load.

We would expect lower internal motor temperatures, which will actually increase your service factor in this operating temperature range (60-77°F). We have performed research at temperatures above and below 77°F with "No-Flow" and the motor has performed satisfactorily. We anticipate no problem with your operating range.

https://cdn.shopify.com/s/files/1/0147/4392/files/pumpman_6.pdf?17343003123420964675


https://cdn.shopify.com/s/files/1/0147/4392/files/pumpman_5.pdf?5463603223447972675
 

shane21

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That may be for Hitachi Cary but Franklin Electric publishes information and they state clearly that "The flow rates above apply when the motor is operating at or less than service factor amperage in water up to 86 °F (30 °C)." when specifically addressing their flow rates. I linked the page below with the Franklin Electric specs but they can also be found on page 6 of the Franklin Electric AIM manual.

https://franklinaid.com/2008/11/26/calculating-minimum-cooling-flows/

Unfortunately, properly designed systems also need to meet specifications of the manufacturer and as I stated in my last post it would be best for the OP to make sure that he verifies with his pump installer that whatever motor he installs, the flow rate around the motor is adequate for cooling.

I do agree that the information published by Franklin Electric is too much of a "one size fits all" requirement because de-rating a motor and running in it well water where the temperature is cooler than the 86° F should allow for less water flow to keep the motor cool but the ratings are printed in black and white and just give installers a reason to deny a warranty and/or claim the premature motor failure was due to inadequate water flow around the motor.
 

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"operating at or less than service factor amperage in water up to 86 °F (30 °C)."

There is absolutely no difference between how a Hitachi and a Franklin are made, except that Hitachi puts more quality in their motor. I am still working from a Franklin book that doesn't have the words "or less than" printed in that statement. Franklin added those words in the last few years to work with their VFD's and because I have been quoting it correctly without (or less than) for a quarter of a century. They don't like it that a VFD creates a smaller motor from a larger one and a CSV de-rates the motor load. However, they still show how a de-rated motor can safely pump hot water, which doesn't take a rocket scientist to understand a smaller flow of cool water would be the same or better. Franklin's motor can handle low flow with low amperage no problem, it is their 25 GPM and smaller pump ends they screwed up.

And the pump/motor manufacturers warranty is NEVER up to the installer or even the supplier. A supplier can issue a courtesy warranty if they want. But there are obvious signs of heat from a lack of cooling like a dropped thrust bearing and rainbow colors on the stator housing. They cannot disallow a warranty because the motor MIGHT get hot, only if the motor DOES actually get hot, which again is as obvious as black or white. The motor tag on a Hitachi turns a different color when the motor gets hot, which is how obvious it is.

Franklin won't put anything about the CSV in writing. They don't have too. They just sit quietly while their army of minions spout myth-understandings and let everybody think things that aren't true, as myth-information is good for the VFD business.
 

shane21

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I know Franklin has been using that infamous "operating at or less than service factor amperage" for over a decade but I don't exactly how long ago they made the change. I just know that as a pump installer I keep up on all the details like this for equipment I install so I don't get stuck in a tight spot having to stand behind my word to a client, and eat the repair bill, because I was too lazy to keep up on the facts or was "sure" of something that turned out to be incorrect when a system failure happens.

I agree that no one submersible motor is somehow radically different than the other and that the cooling requirements of all of them are probably all very similar, I am just informing the OP of details to hash out with the installer so he isn't faced with issues down the road over details he may be unaware of - this is all about educating the consumer about an industry that can get a bad name because consumers don't know the proper questions to ask or how to tell the difference between a good pump company and one who is looking to take advantage of them. I am sure there aren't a lot of installers who keep on all this stuff, hell Cary you seem to be pretty well informed and willing to help people on these forums and even you didn't know about Franklin Electric's cooling requirements, so imagine how often installers are uniformed of this stuff!

I appreciate you thinking "Franklin's motors can handle low flow with low amperage no problem" and maybe they can, but their published information says differently for motors rated at 3 HP and above so why would a consumer ever want to disregard that information and risk a problem? Presenting the consumer with all the information, even the stuff we don't like or "think" doesn't matter, is still part of our duty as professionals in this industry.

I absolutely disagree with you that the installer or supplier/distributor have no say in the warranty process because both parties do have a say if they know a system was designed incorrectly and the failure was not due to a manufacturer's defect. Specifically the supplier/distributor has a major say in this industry because they are offering installers like me a free 5 year warranty, that I then pass on to my customer for free, on a product that the manufacturer may only offer a 18-36 month warranty on. If they are sticking their neck out to help me sell a product then I will absolutely make sure the equipment is installed as part of a properly designed system to help them minimize product returns due to improper installation. You have to remember all these warranties are for products that failed because of a defect of some kind, they have no intention of honoring a warranty when someone installs a product incorrectly, nor should they.

If nothing else I am sure we have made the OP in this thread aware that a CSV and a 3 HP Franklin Electric motor are probably not a good fit for his well and that was my only intention.
 

Valveman

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hell Cary you seem to be pretty well informed and willing to help people on these forums and even you didn't know about Franklin Electric's cooling requirements, so imagine how often installers are uniformed of this stuff!

I now all about Franklins cooing requirements. I wasn’t born knowing this stuff. I learned it from multiple engineers at the pump and motor companies I have worked with through the years. A Franklin engineer named Joel Roach was the first one to explain de-rating the motor load to me. That means a Franklin Engineer told me when the amps are reduced the half a foot per second rule goes out the window. A Franklin Engineer is the one who told me if the amps are reduced enough for the motor to safely pump hot water, it takes very little cold water to keep the motor happy and lasting a long time. The younger Franklin engineers may know that, but they would probably lose their jobs for saying it in black and white like that. Better to make people think a motor needs as much cooling with a CSV as with a VFD, even though that is not the case.

Engineers for both Franklin and Hitachi motors are the one who showed me how to tell when a motor has reached a critical temperature. It is obvious when a motor has been running with a lack of cooling flow.

Pump guys don’t throw a burned motor on the floor at the distributor and say, “Don’t give me a warranty. That pump had a CSV on it and the motor had to have gotten hot”. NO! They demand a warranty and will never admit the pump was improperly installed, ran out of water, or was deadheaded. That is why the manufacturers do warranty inspections. When they open it up and it is obvious it was melted down from a lack of flow, the installer doesn’t want to hear it. The installer is usually angry and screaming for a warranty he knows he doesn’t deserve.

Manufacturers give a lot of courtesy warranties for burned out motors just to keep their installers from being angry. But the manufacturer still can’t disallow a warranty or claim lack of cooling when it is obvious the motor never got hot. Buy a low millage used car from an authorized dealer or just a neighbor, and Ford will still honor the warranty. Buy a Franklin motor from an authorized dealer or on the Internet, and as long as it doesn’t show heat damage or other improper use Franklin will still honor their warranty. It has absolutely nothing to do with having or not having a CSV or any other type of control.
 

Valveman

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I am just informing the OP of details to hash out with the installer so he isn't faced with issues down the road over details he may be unaware of - this is all about educating the consumer about an industry that can get a bad name because consumers don't know the proper questions to ask or how to tell the difference between a good pump company and one who is looking to take advantage of them. I am sure there aren't a lot of installers who keep on all this stuff. Presenting the consumer with all the information, even the stuff we don't like or "think" doesn't matter, is still part of our duty as professionals in this industry.

No, you are just confusing the OP with technical jargon that he doesn’t understand, hoping to scare him to just do whatever his installer says is best. That is the reason the industry already has a bad name. Instead of educating the consumer, many installers lie about a lot of stuff like VFD’s saving energy and making pumps last longer to sell the most profitable item they have. They will also lie about the CSV overheating a motor or causing a warranty to be disallowed. It is not very “professional” to take advantage of customers like that. Of course, the consumer doesn’t know what questions to ask or how to protect themselves. They should just assume every pump company will take advantage and educate themselves in self-defense. It is always best to hear what other customers say instead of the installer or manufacturer. Other customers will tell you what works best and how to save money. Hearing the same thing from an installer as you hear from other customers is how to find an honest company to work with.

Your system requirements are the ideal system for a Cycle Stop Valve. You would only need one pressure tank then. It will also be much less expensive than a VFD.

If nothing else I am sure we have made the OP in this thread aware that a CSV and a 3 HP Franklin Electric motor are probably not a good fit for his well and that was my only intention.

Only one of you can be right. Only one of you agrees with all these customers. :)

https://cyclestopvalves.com/pages/reviews

http://forum.cyclestopvalves.com/index.php?board=25.0



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