New Pump Question

[Cclittle]

Hi everyone, it's time to do something about my wife's complaints about low water pressure.
Our well currently has a 1/2 hp 12 gpm Franklin pump that was put in some 14 years ago. It's at 85 feet in a 4 inch well that is 103 ft deep and has a water level of 50 ft. When they did the well, the water level was apparently still 50 ft after pumping 15 gpm for an hour. I have a 34 gal bladder tank that tests out ok. The pressure switch is 40/60, and the pump seems to work just fine - on at 40, off at 60. A bit slow, maybe.

But there are times when even with a few household things running, my wife gets low pressure at whatever she's in front of. Never mind when the sprinklers are running. 8/10 of an acre, with 8 zones of 6 heads each, 3 gpm heads at 40 psi. Only they don't get 40, they get about 24, and the pump can barely keep up. I have dead spots between sprinklers because they can't throw as far as intended (36 ft between heads). I don't need to run them and the house together, as they run at night, but I do need full power to what's going on at the time.

So I need a pump that can provide the psi, but I'm not sure I want to chance it with more than a 20 gpm pump. Judging by the curves, a Franklin 3/4 or 1 hp would provide lots more pressure. The curve on a 1/2 just sucks for providing higher psi. But should I go with a 15 or 20? A 1 hp 15 gpm would be conservative on the drawdown and give great pressure at its full gpm. But 15 doesn't seem like much more than 12...

I'd also redo some of the internal plumbing from the wall to the softener to reduce restrictions and add a CSV.

That should do it, right? Thoughts guys?

 

[Reach4]

I think a 3/4 HP 10 GPM pump would be a good match for you if you go to 2 GPM sprinkler heads. Your current pressure tank would be a little under-sized.

 

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[Valveman]

A 3/4HP, 10 GPM might do if you change out the sprinkle nozzles. But I would go with a 15 or 16 GPM in a 1HP. The CSV will make it work like a small pump when a small pump is all you need, but that pump can supply 18 GPM to your sprinklers so you won't have to change the nozzles. Turn the pressure switch up to 50/70 and set the CSV at 65 PSI. This will be such strong constant pressure the wife won't even need soap in the shower anymore as it will just blast the dirt off. Happy wife, happy life.

 

[Cclittle]

You're kidding about 65 PSI right?

Here is a diagram of what I have in mind inside and a pic of the current setup. I'd like to open things up in the middle of this to be all 1.25" and replace the hard 90's with longer radius ones. And replace the 1" to .75" to 1" that currently exists to the sprinkler.

So does my plan check out?

 

[Reach4]

He was not joking about 65 being quite doable, but since things are adjustable, you can change things later. 80 PSI max.

No need for longer radius elbows in a pressure system. While doing stuff, I would get rid of the galvanized tee and other galvanized while you are in there. If you keep that pressure tank but are rearranging your piping, I would maybe raise it a bit on a big-enough concrete paver and have the drain valve lower with respect to the tank. That valve gets used to blow out sediment that might collect, so you would like it lowest. You would like to be able to put a hose on that and wash out whatever. I am not a pro.

 

[Valveman]

Yeah NO, not kidding about 65 PSI. But like Reach says you can adjust it down as much as you want. With the CSV you just have to start out with a pump that is plenty large for all your needs, then the CSV will tune it down to whatever you want it to do.

15 or 16 GPM in a 1HP will deliver more pressure than a 20 GPM series.

 

[Cclittle]

Valveman - I should probably ask: since I'm replacing my pump after I do the work inside the house, do you have any recommendations for which one I should get? I've been looking at the Franklin Series V 15 GPM 1 HP (2 wire). Any issues there? If so, what do you recommend in those specs (and general price)?

 

[Valveman]

Franklin has cheapened their pumps up so much that I recommend just about anything but a Franklin. A 16S10-10 Grundfos would be my favorite. But a Goulds 13GS10 or a Pentair 15 GPM, 1HP would also work.

 

[Cclittle]

Wow, so the traditional local well guys wanted $400-500 more for the Grundfos than a comparable Franklin.
But I see I can get the Grundfos 16s10-10 on Amazon for about $800 and have Amazon Home Services install it for $400. That's about the total cost the local guys want for a Franklin, installed. That seems like a good deal, right? Then I'm just not paying the local guys product markup...?

Oh, and question on back pressure... should I be worried about CSV back pressure being too high with the 16S10? My water level at 50 ft. I don't know what the drop pipe is, but I have 1" black poly coming into the basement.

 

[Valveman]

With a static of 50', a 16S10-10 will only make 108 PSI back pressure. Should not be a problem for any kind of pipe.

Let us know more about this "Amazon Home Services". I'm assuming they use a local and licensed pump guy to conform to regulation? Sears tried this many years ago, and I don't think they had much luck.