Recommendations for Best Path Forward On Well Pump Control Setup

[Sef]

Hello all!

I was hoping to get some recommendations/insight on what is my best path forward on a pump control setup for my new residential home construction.

A little backstory:

We had a well drilled on our lot back in February and had to get a flow test for bank loan requirements. We ended up going with the same well pump installer that all the other neighbors went with since they all were happy enough with the results. The installer went ahead and installed a Grundfos 16S30-24, 3 phase, 230V, 3 HP centrifugal pump. At the time I had little understanding of well systems and didn't have the time to get up to speed since we needed to get the loan rolling.

Fast forward to today and we are getting ready to install the pump control system and associated items (VFD, pressure tank, etc.). The installer wants to go with a Pentek Intellidrive PID-30 VFD controller and an 81 gallon pressure tank. However, since the pump install I've had some time to do enough research to notice that many folks are suggesting that VDF systems are perhaps not the ideal solution, but rather it is more effective to go with a more traditional setup with a Cycle Stop Valve to get the benefits of a constant pressure system. But it also sounds like I may be stuck with a VFD setup unless I pull the current 3 phase pump and swap with it for a single phase one?

I feel that I have done enough research to be dangerous, so my question is, should I simply move forward with the VFD setup and re-address this when it eventually fails, or does it make more sense to pursue a different route?

If it helps, below are my well specs that I have on hand:

Well diameter: 6 inches
Drop pipe: 1 1/2 SCH 120 PVC w/ S.S. Couplers
Depth: 540 feet
Standing Water Height: 175 feet
Pump Setting: 428 feet
volume test (required by bank) showed 23 GPM over a 2 hour flow period.

Cheers!
Sef

 

[Valveman]

Pump man already hooked you up with a tar baby. With a 3 phase motor you don't have much choice but a VFD. Good thing to have an 80 gallon tank cause the PID doesn't really work like a VFD. It still cycles the pump on/off every 60 seconds or so. Constant pressure is a good thing. When you tire of the expense and waking up with no water switching to a single phase motor would allow you to use a simple, inexpensive, and long lasting Cycle Stop Valve to do that for you. You will notice that the PID doesn't really supply Constant pressure.

 

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[Sef]

Thanks, Valveman, that's what I feared.

Here's a quick question for you, I'd love to hear your thoughts. What if I were to install a relatively simple, no-frills VFD to simply turn the pump on and off (almost acting like a phase converter but with some added benefits like soft starts and speed limiting) and added a CSV setup (PK1A or similar), using the 40/60 pressure switch as a digital input into the VFD as an on/off control.

I realize this would be a very backwards way to do things, but I could see this being less expensive than the PID-30 setup and create less wear on the system?

 

[Reach4]

Pump man already hooked you up with a tar baby. With a 3 phase motor you don't have much choice but a VFD

You used to like Single Phase to 3 Phase Converter for this. Did those turn out to be problematic?

 

[Valveman]

Can be done with a phase converter and a CSV. They are a little less problematic. But they are not much different than when set up as a VFD. Still a technical mess compared to a regular single phase motor and a CSV.

 

[Valveman]

Thanks, Valveman, that's what I feared.

Here's a quick question for you, I'd love to hear your thoughts. What if I were to install a relatively simple, no-frills VFD to simply turn the pump on and off (almost acting like a phase converter but with some added benefits like soft starts and speed limiting) and added a CSV setup (PK1A or similar), using the 40/60 pressure switch as a digital input into the VFD as an on/off control.

I realize this would be a very backwards way to do things, but I could see this being less expensive than the PID-30 setup and create less wear on the system?

It would be more dependable than counting on a VFD to do everything.

 

[Valveman]

Usually when people tell me they have replaced the expensive VFD 2 or 3 times in say 5-10 years but still don't want to go to the expense of pulling the pump and replacing the 3 phase motor with a standard single phase motor, I recommend a phase converter. This is usually done with a cheap VFD. You can get an inexpensive VFD from driveswarehouse.com, set it to work like a soft starter, and use a Cycle Stop Valve and regular pressure switch to control the pump/motor. It is much less expensive than a VFD from the pump manufacturer and In this way you have the CSV and everything needed to control the normal single phase motor when the 3 phase motor fails, or you just get tired of the expense and water outages from the VFD.

 

[Sef]

Sounds good! I will likely go that route for now.

I'm in the process of specing out a suitable VFD. In the meantime, it looks like the PK1A Pside-Kick is likely the setup that would work best for my needs with the exception of minimum water level? With an 18 gpm pump (mine is 17.6 gpm) your site recommends a minimum 200' water level, mine was measured at 175'. is that difference sufficient to need a modified CSV setup?

This setup will also be running my irrigation system. From what I've read in other posts, this shouldn't have a problem with that, correct? I would simply plumb in my irrigation line downstream from the CSV.

 

[Valveman]

Sounds good! I will likely go that route for now.

I'm in the process of specing out a suitable VFD. In the meantime, it looks like the PK1A Pside-Kick is likely the setup that would work best for my needs with the exception of minimum water level? With an 18 gpm pump (mine is 17.6 gpm) your site recommends a minimum 200' water level, mine was measured at 175'. is that difference sufficient to need a modified CSV setup?

This setup will also be running my irrigation system. From what I've read in other posts, this shouldn't have a problem with that, correct? I would simply plumb in my irrigation line downstream from the CSV.

175' is better than (minimum 200'). Any tee after the CSV will deliver constant pressure. Sounds like you are on the right track. Thanks!

 

[Sef]

Okay, I think I'm working things out nicely.

Now I have a new question. I looked over the plumbing in the house and it looks like its poly tubing from the well head to the crawlspace, but my plumber decided to run a pex line from the planned pressure tank location to meet up with the poly. With the new plan to install a CSV, there will be a portion of pex between it and the well pump. This feels like it might be an issue with the backpressure produced by the CSV? Should I get them to run poly all the way to the CSV, can I just have them install the CSV in my crawlspace as the junction between the poly tubing and the pex?

 

[Reach4]

A section of PEX after the CSV should not be a problem, if 1 inch or bigger PEX. Maybe 3/4 would be adequate, but even 1 inch PEX is smaller ID than 1 inch SIDR polyethylene pipe.

 

[Sef]

A section of PEX after the CSV should not be a problem, if 1 inch or bigger PEX. Maybe 3/4 would be adequate, but even 1 inch PEX is smaller ID than 1 inch SIDR polyethylene pipe.

I'm not concerned with pex after the CSV (otherwise I would be sin a heap of trouble as the whole house is plumbed with pex). I'm more concerned with the pex that is before (upstream from) the CSV as I'm afraid it won't withstand the backpressure created by the csv?

 

[Reach4]

Concern about the backpressure is warranted. Are there markings on the pipe? You could momentarily pump into just a 200 psi gauge, and see what the pressure at no flow is.

How much current flows on one of the wires out of the pressure switch when the pump is pumping? That will probably distinguish if it is 1/2 hp or 3/4 hp.

 

[Sef]

The installed pump is a grundfos 3 hp, 3 phase motor. (Link to pump)

 

[Reach4]

The installed pump is a grundfos 3 hp, 3 phase motor. (Link to pump)

I see you listed your pump in the first post. The Grundfos 16S30-24 can produce over 300 psi into the drop pipe. Even after rising 170 ft. the pressure is about 230 psi. So even if the drop pipe was PVC, it would be important that the pipe after the pitless to the CSV be rated 250 psi I think. Now if we presume a working variable speed control keeps the pressures from getting that high, then things could work.

Also, the CSV has a maximum rated pressure drop between input and output. I am thinking maybe 150 psi for CSV1A.

 

[Valveman]

Hello all!

I was hoping to get some recommendations/insight on what is my best path forward on a pump control setup for my new residential home construction.

A little backstory:

We had a well drilled on our lot back in February and had to get a flow test for bank loan requirements. We ended up going with the same well pump installer that all the other neighbors went with since they all were happy enough with the results. The installer went ahead and installed a Grundfos 16S30-24, 3 phase, 230V, 3 HP centrifugal pump. At the time I had little understanding of well systems and didn't have the time to get up to speed since we needed to get the loan rolling.

Fast forward to today and we are getting ready to install the pump control system and associated items (VFD, pressure tank, etc.). The installer wants to go with a Pentek Intellidrive PID-30 VFD controller and an 81 gallon pressure tank. However, since the pump install I've had some time to do enough research to notice that many folks are suggesting that VDF systems are perhaps not the ideal solution, but rather it is more effective to go with a more traditional setup with a Cycle Stop Valve to get the benefits of a constant pressure system. But it also sounds like I may be stuck with a VFD setup unless I pull the current 3 phase pump and swap with it for a single phase one?

I feel that I have done enough research to be dangerous, so my question is, should I simply move forward with the VFD setup and re-address this when it eventually fails, or does it make more sense to pursue a different route?

If it helps, below are my well specs that I have on hand:

Well diameter: 6 inches
Drop pipe: 1 1/2 SCH 120 PVC w/ S.S. Couplers
Depth: 540 feet
Standing Water Height: 175 feet
Pump Setting: 428 feet
volume test (required by bank) showed 23 GPM over a 2 hour flow period.

Cheers!
Sef

If the water draws down to 420' where the pump is set, then that is the right size pump for 14 GPM at 50 PSI. However, since the well made 23 GPM for hours, I doubt the water level will drop much lower than the 175' static level. Knowing the water level while the well was being tested for hours would have let you choose the right pump. Without that number, they just install the largest and most expensive pump needed for the setting depth. And yes, with that pump and a water level of 175' there will be 230 PSI on the CSV and pipe prior to the CSV.

That size pump needs a minimum of 350' of head to keep the impellers out of an upthust condition. From 175' and 50 PSI (115'), that is only 290' of head. You will need to either restrict flow to 20 GPM or slow down that pump so it doesn't upthrust when the water level is high. Since you are having to use a VFD as a phase converter anyway, just set the max hertz to 54 hertz instead of 60 Hz. This will reduce the pump/motor speed by 10% and the head by 19%. Upthrust will no longer be a problem and the back pressure on the CSV and the pipe prior to the CSV will be reduced to 176 PSI, which is acceptable for the CSV1A-3 and most pipe.

If that is enough water and you ever have to replace that pump, go back with a 2HP in the 16S20-18, which is basically what you are making out of the 3HP at 54Hz.