First time well user, new install questions

[tenflyer]

Good evening.  I'll provide the background here and I wanted to run some something by everyone.  The to-be-built house will be a 5 BR, 4 bath with one of the showers being a multi-outlet deal that alone could use up to 15 GPM (if all heads/sprays were turned on at the the same time which won't be frequent but I do want to provide for this).  So I know we want to size our system to support ~ 20 GPM at a steady 50 or 55 psi.   Probably use 400-500 gallons a day average.  House is 3 stories with the basement so I know I need to consider the extra ~ 30 feet there.

The well was dug last week, it is 8" wide, 500 feet deep and static water level is about 55 feet.  Unfortunately the yield is only 1 GPM.  So at first I thought we'd need to add 300-400 gallons of storage in our basement and add a booster pump, but the more I read I realize hey the well itself will have probably 1,100 gallons in it when full so that is our storage.  Then we come to find the property had an existing well on it dug back in 1988.  That one is 340 feet deep, about 55ft static water level and according to the permit had a 2 GPM yield.  I'm going to work with the county to figure out if I can use this old well (I was first told it needed to be abandoned for some reason).  I know I would also need to do a yield test on it etc. of course.

But for now I was assuming I can only use the new well.  If I understand my research (and again I never had a well before so bear with me) I'd want the submersible pump at about 480' deep.  To support 20 GPM I 'think' I'll need something like a Grundfos 16S20-18 2HP and add a PK1A Pside Kick.  (Originally before I found this site I was considering something like the Amtrol Wellxtrol 80 gallon to provide the constant pressure we'd want).  Our home builder was pushing the variable/constant pressure pumps but I now know enough to steer our system to a CSV.

What else am I missing? Am I sizing things properly?  Was thinking, again assuming I don't have to abandon the old well I could always add that later if we need it.   Given the low yield of the new well, is it critical to get that old well approved for use and tap into that with a 2nd pump right from the get-go?   Saw on your site how that would work with two CSV's and just slightly stagger the pressure switches between the two.    Again apologies for my novice questions here, this is our sixth house but first well so this is something I never had to think of before.

Thanks in advance!

[Cary Austin]

Well a 16S20 will produce 15 GPM from 380' of head.  So it would still produce 15 GPM at 60 PSI until the water level was pulled down to 250' or so.  This would allow a 15 GPM shower to be used for only 20 minutes before the well is too low.

To be able to utilize all the stored water in the well (20 GPM from 480' at 60 PSI) you would need a 5HP, 30 GPM series pump.

The 2HP will have a back pressure of 216 PSI, because of the 50' static level, but the CSV1A can work with that.  The higher the pressure setting, the lower the differential pressure, which is good.  So you could run a 60/80 pressure switch with the CSV holding a steady 70 PSI.  I would use the larger 10 gallon size tank with the PK1A kit because of the higher pressure.

The 5HP, 30 GPM pump would have 281 PSI back pressure.  You would need a CSV2W 50-120 (red seat) valve to work with that size pump at that pressure.  The 5HP will need a minimum of 5 GPM to stay cool, which is the minimum in the CSV2W.  This means it would also need a little larger tank, as it would also be filled at 5 GPM.  At 60/80 pressure with a 5HP pump, I would use a minimum of a 44 gallon size pressure tank.

Another option would be to install a 1HP, 5 GPM pump in the well and use it to fill a cistern storage tank.  Then a little 25S10-7 1HP pump in the cistern tank could supply as much flow and pressure as you need.  A 500 gallon cistern would run the 15 GPM shower for 33 minutes, a 1000 gallon cistern would run the shower for 66 minutes at a time.  Running this pump  at 60/80 I would also use the 10 gallon size tank on the PK1A kit.

[tenflyer]

Cary - I appreciate the thorough response that actually all makes sense to me.  I can see the pro's and con's of both options, either one expensive deep pump or two smaller ones. Trying to think of what would make the most sense long term.

So you recommend a submersible in the cistern and not an external booster pump?

[Cary Austin]

I use subs for everything.  They are quite, don't loose prime, and give more production for the horsepower than a jet pump.  but either will work.  The cistern and booster will take a lot of wear an tear off the well pump.  Plus a low level alarm in the cistern would give you a few days worth of water to live on while you are waiting to get the well pump repaired.

You could also rig it to where you could run the house from the cistern pump or directly from the well.  With the small pump in the well you wouldn't have a lot of water to use, but it would be better than nothing on a day when the cistern pump failed.

[tenflyer]

And so just a few minutes ago my builder's well/pump subcontractor just proposed a 1 hp goulds 10SB10422C and a 119 gallon pressure tank as kind of the starting point.  I don't think that would work properly at all for us. 

Options were to add an AquvarSold Goulds 1AS16 constant pressure system to this.  From what I've read I don't have any interest in that, so scratch that one.

Another option was to add a 290 gallon storage tank w/ float valve using a 3/4hp Grundfos 15SQE07-180.  I think that gets closer to what we are talking about here at least but then again not really since I think that is a variable speed pump and I'd rather suggest/push for your outlined scenario.

So just like I've been reading on your site and others some companies just push these electronic/variable speed pumps and controls.

[Cary Austin]

So just like I've been reading on your site and others some companies just push these electronic/variable speed pumps and controls.

Yes they do!  They make a lot of money on variable speed pumps, and most people are easily duped by all the fancy promises.  You certainly do not want a SQE, Goulds Aquavar or any other variable speed type pump,especially just to fill a storage tank.  Any pump man that suggest that should be covered with tar and feathers.  Variable speeds are made to vary the flow, which doesn't happen when you are just filling a storage tank.  The goal here is to get you a dependable water supply, not to make the installer a bunch of extra money for nothing.

[tenflyer]

So I think what I'm going to 'counter propose' to the well guy is (they seem to have a Goulds preference) 5GS10 1PH in the well (I assume that will need to be down pretty deep, not sure there), that will fill the ~ 600 gallon cistern tank in the basement.  Add a 25HS10 to the tank (with the float switch etc) then a PK1A Pside Kick outside the tank for the constant pressure.  Sound perfect?  Maybe the 25HS10 is overkill and the 18HS10 would suffice.

Depending on where their pricing comes in if I have $ left I might have them add a PK1A Pside Kick before the cistern with extra valves to handle the situation you highlight that the tank pump dies and we need a temporary alternative. 

I have a feeling I'm going to have to send them the diagrams from your site 

[Cary Austin]

Sounds good to me.  The 25HS is not a problem in that the CSV will let you install as large a pump as you think you need, and the CSV will make it work like a small pump when small amounts of water are being used.

[tenflyer]

Hi Cary, one more question and again I'm a novice when it comes to this.  According to the well report my static water level is 90' (not 55').  The depth of 500 and yield of 1 GPM is still the case.  During the test the drawdown took the water level down to 241' in 75 minutes (they started pulling at 7.5 gpm and took it down to the yield of 1 gpm).

Assuming I still stick with a  600 gallon tank in my basement, does that change anything outlined here?  And my dumbest question ever is what depth would the well pump be set at optimally?  If I have the tank in the basement I won't need necessarily need the full 1000 or so gallons in the well bore for immediate use.

Thanks again.

[Cary Austin]

If you use a storage tank you will need a 25 GPM, 1HP like the 25S10 in the storage tank using the CSV to supply the house.  But then all you need is something like a 5 GPM, 3/4HP at about 300' in the well to supply water to the storage tank.

[tenflyer]

Awesome Cary thanks for you help I'm getting it now!  I'm actually researching a hydrofrack for this well too, just got the cost estimate and I think it may be the right call this company has had some great success in the area.