Help with well pump options

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Old 03-22-16, 01:10 PM
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Help with well pump options

I have a new domestic well that is 205 with static water level at 56 (drilled and measured in Sep after 2 years of drought). It is a 6 well casing with 4 PVC liner with 40 3/4 perfs from 165 to 205 sitting in mostly gray shale. The bail test indicates 6gpm. Im building a residence that is under 2500 sq ft with just two adults. We will have a small garden and possibly some yard watering in the summer though the area is pretty shady with many trees and a creek nearby. We are in rainy Western Washington State. I have two very different estimates on pump size. One company suggests a Goulds 1hp 10gpm 12 stage (10GS10). The installer thinks the static level allows for a bigger pump which will somehow be more efficient as its gpm start at 10 but tapers down to 6gpm as the water level drops. The other installer suggests a Flint & Walling 1/2 hp 5gpm 15 (4F05S05) stage and says it will operate at the best efficiency and not overdraw the well. Can any of you offer opinions/advice as to which idea is more sound? Thanks for your help.
 
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Old 03-22-16, 01:45 PM
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Welcome to the forums.

Luckily I'm on city water so I don't have a well and I'm not an authority on them.

It would seem to me that the 1hp would be spending a lot of time starting and stopping with minimal water usage. You don't appear to have major water requirements. I would lean towards the 1/2hp pump.

There are many members here on wells and they'll stop by and add their opinions.
 
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Old 03-22-16, 04:27 PM
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Is this going to be a standard pressure tank setup or variable speed, constant pressure continuous run?

Do you know if you will need any water treatment, like filters that require back-flushing? 5GPM is on the low end for back-flushing sand or media filters or the like.
 
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Old 03-22-16, 04:44 PM
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Good points Paul. Maybe that would indicate a 3/4 hp would be more beneficial.
 
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Old 03-22-16, 05:01 PM
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It will be a standard pressure tank setup and, luckily, the water is excellent, no one in the area uses any filters, neutralizers, etc.
 
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Old 03-22-16, 05:16 PM
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As a Real Estate Broker, I once sold a Horse Farm with a drilled well that only produced GMP. The people buying it were bringing 27 Norwegian Fjord Horses with them from Idaho, and were concerned that they might run out of water.

But that was in 1991, and in the past 25 years, they never ran out. They had a big pressure tank that served as a reservoir and even at only GPM, that's still 720 gallons of water per day . . . . that's a lot !
 
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Old 03-22-16, 05:43 PM
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If you look at the chart for your 1/2 hp option you'll see that it produces about 9 gpm at 100 ft water depth, well below your static water depth which looks good. But, if the water level in your well drops it's down to the bottom it's still producing 7 gpm. Not to shabby. I would say it's a good fit for your well. Yes, more is sometimes better but you are limited in how long you can pump more than your gpm recharge rate before you run out.

Here is the .pdf for your Gould candidate. When you look at the performance chart for the 10GS10 you'll see that it's recommended depth doesn't begin until you get down to about 175 feet and at that point it's producing 16 gpm. Looks like overkill for what your well can produce.
 

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Old 03-22-16, 06:05 PM
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Not sure if I got the attachment process right but I uploaded the charts for these pumps in this posting and am confused by the difference between the charts and the efficiency graphs. Looking at the 60psi discharge the gpm is lower than on the efficiency graphs. What am I missing?
Name:  Pump chart comp.jpg
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Size:  53.6 KB
 
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Old 03-22-16, 10:16 PM
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Your well is almost identical to mine, except I don't have shale, therefore no perf liner.
Are both those pumps 230V? I would go with a 3/4hp or the 1hp...
And did you say what setup you had in mind (variable speed pump or a pressure tank)? Neighbor has a variable speed Goulds...wasn't impressed with his GPM (4gpm - deeper well).
I went with pressure tank because the pump is cheaper, and we have power outages, and so, I still have water while BC Hydro takes their sweet time fixing the lines. Eventually, I'll hook up well shed to genny....
You say the bail test indicated 6gpm? What is that? I'm skeptical of the number considering where you live. I put my 3/4hp pump on full tilt through a 1" line and I couldn't get past 115ft (205 deep well, 70 static level). My flow was 10+gpm.
Although, I live in a rain-forest for half the year, we have dry spells, and I want the extra oompf in case of a forest fire, and irrigation.
With a pressure tank, it doesn't really matter what you get...just takes longer for tank to refill, unless you exceed flow rating of pump. I plan to irrigate, and with 4 sprinklers going, I will exceed my pumps capacity. For everything else, I will never exceed the pumps capacity (except a forest fire situation).
BTW - I doubt you could run the well dry with a 1hp pump...provided your not on top of a mountain.
 
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Old 03-22-16, 10:26 PM
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I meant air test, not bail test. Yes both are 230v and I expect to use a standard 81 gal pressure tank. We do have a similar climate to you in beautiful BC. What depth is your pump set at? Your well must have a quick recharge time. I appreciate hearing your experience.
 
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Old 03-22-16, 11:23 PM
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I have my well at about 185ft-190ft...I am going to raise it ten feet, as I got a bit of AL/FE...might be the bentonite that got washed in hole or I'm picking up sludge off bottom or the rock is laden with the above.
Recharge time is meaningless for me, as I can't get below 115ft (point at which inflow equals outflow). If I recall, it takes about 5min to climb back up to 85ft (summer). In winter, I am at 70ft.
We had a serious drought last summer, but our water tables didn't really drop much at all. They have fully recharged over this winter!
If you are the west side of the Cascades, I doubt you could ever run dry with a 56' static level. Here is my thread on my setup:
http://www.doityourself.com/forum/we...ml#post2331739
 
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Old 03-24-16, 11:32 AM
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The thing about these curves is you that need to include the pressure you want in your system as total head so I'm not looking at 200' but more like 320' when pressure is included, thus the actual gpm for this pump would drop below 5pgm at its lowest. The chart (sent earlier in the thread) that includes psi indicates that more clearly. Thanks everyone for your input. It has been very helpful.
 
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