Opinion for flowing artesian well set up.

[ZombieBeaver]

Single family home. No kids, but we water various animals each day.

We had a new 400' 6" well drilled and installer installed a Goulds 7gs10 pump with 1hp motor simply due to installation depth of 380'. Now that well has settled in over 4 months or so we understand the true nature of the well. It is a flowing artesian with 1.2 GPM out the top and positive pressure at the cap of 10 psi. Well recharge at the bottom was estimated at 9.5 GPM when drilled.

Pressure tank is a wx-205 running 30/50, no CSV.

Since well is typically completely full of water and under 10 psi of pressure with a sealed cap, the pump which is supposed to run 2 to 10 GPM is filling my 10 gallon well tank in 30 seconds (20gpm!) Installer claims it's fine no problem and doesn't want to deal with me. To prevent overcurrent, reduce upthrust, and increase run time, I installed a 10 GPM Dole valve before the pressure tank to throttle the pump back so now I have one minute fill.

I'm trying to determine my best course of action, and was considering some combination of the following:
- Replace pump with a Red Jacket 6S25 (seems better sized for the situation)
- replace pressure tank with larger wx-251 for double volume.
- install CSV

Any initial opinions? Either way I'm losing money on something. They won't take the pump back or admit it's not size properly for the application. If I hadn't installed the dole valve I'd still be flowing 20 GPM with a 30 second run time.

EDIT: additionally I'm worried about throttling the pump back even further. From the pump curves it seems to me I'd have about 178 PSI of line pressure if the CSV were to throttle back to two GPM. The line is 35 years old and is already seeping a bit at the fitting where it enters the basement due to the Dole valve I had already installed...

EDIT2: after running all calcs including pressure loss in pipe and fittings etc I arrive at my best and worst case scenarios of 90 ft head (BEST) and 525 ft head respectively (WORST assuming I actually drew the well down to near the level of the pump, which I believe is probably unlikely). No pump can handle such a wide range and stay in it's ideal operating region without some creative restricting going on.

 

[VAWellDriller]

A 7GS10 will not pump 20 gpm. There may be something else going on to create the short cycle, but that pump wont pump that much.

It is a little tougher to properly design a pumping system with such high fluctuations in water level. I see a lot of times drillers that just airlift, underestimate the yield (and also have no idea where it is coming from). I doubt it would draw down to 380' at 9.5 gpm, but the only way to know is to pump test.

A larger tank is one answer as you mentioned. You could also install a VFD to control the pump, or since you are worried about old piping, you could install a CSV in the well under the pitless.

 

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[Valveman]

Actually that pump will do 225 PSI back pressure from a flowing well. That is more pressure than the in well CSV can handle. I also agree it is probably more than your underground pipe can handle, so installing a higher pressure CSV at the house is not an option either. The 10 GPM Dole valve was a good idea. Now you just need an 86 gallon size tank, as it will hold 20 gallons of water and give you 2 minutes of run time. That would be the way to make what you have last the longest. For a tank to hold 10 gallons of water it would need to be a 40 gallon actual size tank.

A VFD works well with a pump that is so oversized and made for 500' when the water level is at 1'. However, the VFD would solve the cycling problem while adding a dozen other problems that will shorten pump life and cost you a lot extra. Just add another 40 gallon tank to the 40 gallon tank you already have, or get an 86 gallon size tank. Then when your pump fails go back with a 7 GPM, 1/2HP instead and there won't be too much pressure for a Cycle Stop Valve.

 

[Bannerman]

You didn't mention the distance from the well to the house.

Assuming the drop pipe within the well is new and has sufficient pressure rating, perhaps replacing the 35 year old section between the well and pressure switch to allow placing an appropriate CSV(s) within the basement would be a reasonable option.

 

[Reach4]

the pump which is supposed to run 2 to 10 GPM is filling my 10 gallon well tank in 30 seconds (20gpm!)

WX-205 is a 34 gallon tank with around an 8 gallon capacity between cut-in and cut out. So 30 seconds would have been around 16 gpm.

With what you have now, keeping your Dole valve and using a significantly bigger pressure tank would be good IMO. You could parallel your existing tank if you keep the path big and short. Putting the pressure switch between the two tanks might be ideal.

Unfortunately the big WX tanks are in short supply. Lowes carries AO Smith, and their description looks good.

In the future, knowing how high your static water level is, a 7 to 10 gpm 1/2 hp pump will probably be a better match.

 

[VAWellDriller]

You might not even care, but for what its worth, I don't think you have a 7GS10 installed. I think it's a 10 gpm series pump, which would be a better fit for the well, and explain the 16-20 gpm you are getting. Without pulling the pump to verify; do a bucket test with a short hose right on the tank....once you get pressure off tank, if you're still getting any more than 10 gpm, you don't have a 7 gpm pump installed....you've got to remove dole valve of course.

 

[ZombieBeaver]

So many great replies. I'm going to read through them more carefully later, but for the moment:

Yes I do have that pump installed. I helped the guys pull it out three times while they were trying to get the grouting to hold against the artesian pressure. Kept blowing out until we finally Portland cemented it in. I have many photos of it with the label.

You may be correct on the flow rate. 16 GPM sounds more realistic if the drawdown is closer to 8 gallons. I thought the drawdown on a 20 psi differential was 9.9 GPM on the wx- 205.

I already have a brand new wx-251 in my hands. It's just sitting there in the box still.

The drop pipe in the well is schedule 120 rigid pipe.

Distance from the well to the house is about 200 ft with no elevation change. All one inch poly with six total 90° bends if you count the elbow in the manifold itself to get into the bottom of the pressure tank.

I'm leaning toward the suggestion of putting the larger wx-251 tank which I already have in hand, forgo the CSV, and wait for the pump to eventually fail. At that point probably drop down to a smaller pump as suggested. Just wondered if maybe I should do that up front. Maybe someone would want a low hours used goulds 7GS10 if I pull it now.

 

[Reach4]

You may be correct on the flow rate. 16 GPM sounds more realistic if the drawdown is closer to 8 gallons. I thought the drawdown on a 20 psi differential was 9.9 GPM on the wx- 205.

Yes, that's what the document says, at 30/50, which you are running. At 40/6o the thing says 8.6. But from there, you are not normally totally emptying the tank before the pump cuts back on. So maybe in practice it is more like 9. Without your Dole valve you are operating in a region of the curve that they don't really draw out any more.

 

[ZombieBeaver]

Thanks for the replies everyone.
Going to swap in a larger pressure tank this weekend and keep the 10 gpm dole valve for now. Pressure tank is original from 1987. Maybe in the future will consider different pump if it comes to that.
I'm also installing a Well Buster artesian well packer to replace the sketchy pressure cap that's about to push off the top of the casing and keep my casing from freezing this winter.

 

[Valveman]

If you are pulling the pump anyway, might as well get the right size pump. With the right size pump using a CSV will save enough without needing the large pressure tank to make up a lot of the difference. Plus it will work better.