Well pump recommendations

Discussion in 'General Discussions' started by LittleJohnny35, Dec 16, 2010.

  1. LittleJohnny35

    LittleJohnny35 New Member

    Ive decided im going to replace my 1.5 hp well pump I have this summer with a smaller more appropriate sized one. I thought it post some info about my setup and see if anyone has any recommendations.

    My well record has the following info dated 2008

    pumping method: submersible
    pump intake set at 45 meters (135feet aprox)
    pump rate: 45 Litres/min (12 gallons/min aprox)
    duration of pumping: 1 hour
    final water level end of pumping 15.78 Meters (47 feet aprox)
    Recommended pump depth 45 1/5 meters (135 feet aprox)
    static level: 15.78 meters
    water found at depth 66 meters
    Theres more info but its not clear

    My house is about 70 feet from my receiver well and my tanks is in the basement.
    I have a 3 ton envision waterfurnace and will probably set my flow to 6gpm
    My house is a 3 bedroom bungalow with three bathrooms but only two occupants
    I have a water softner in case that matters when it comes to regeneration.
    My current well pump is a Pompco ST20-150-233 which I linked on this post. I would like to get another pump from the same family of pumps but either a 1/2 hp or 3/4 hp. What do you guys think is a good size for my set-up? If you need more info just let me know. Thanks :D

    http://www.pompco.com/Document/BD submersible pump ST - SL.pdf
  2. waterpirate

    waterpirate Well-Known Member Industry Professional Forum Leader

    I am gong to assume and take some big liberties about the way you want to live your life. YMMV

    We normally size a 10gpm for average size homes with 2 adults and 2 kids, 2.5 baths. That 10 gpm only needs to deliver a working pressure of 60 psi to provide city like performance. Your current pump is grossly oversized IF the well pumping information is correct in identifying a working pumping level around 50 feet.

    So your geo needs 6 gpm and your house needs 10 that makes 16 gpm needed at 60 psi. I am not familiar with that brand of pump so we will size using thier chart only. I would recomend a 18gpm 3/4 hp pump based on well info provided. That cuts your motor hp by half and you consumption even more. Contact Franklin electric which Pompco uses to drive thier water end and they can provide consumption data to you for that motor.

    Hope this helps
  3. LittleJohnny35

    LittleJohnny35 New Member

    Thanks for the reply Eric. I just want to clarify the well specs in case im misinterpreting my well sheet or incorrectly writing it here. I did some reading to try and decipher my well info so I could understand better how a well pump is sized. I found a site that states the following info is required in order to determine proper well pump but im not totally sure im applying my well info correctly. Im copying what they ask and showing how i think my well info is applied

    First step: take the house pressure needed and multiply it by 2.31.
    This will determine the head pressure needed for the house.
    For our example we will use 60 PSI.

    In my case I would also use 60 psi so this would be 138.6

    Second step: figure out the depth you will be setting the pump.
    Most pumps are set 20 feet off the bottom of the well.
    Sometimes the pump is set higher than 20 feet off the bottom if the static (standing) water height is close to
    the surface (a well with a 6-inch casing contains 1.347 gallons of water per foot).
    For our example we will use 200 feet.
    200 – 20 (feet off the bottom) = 180 feet of head.

    In my case from what i read on my well sheet I would be 136.5 feet (45.5m)

    Third step: add up how many stories you will be pumping the water up to.
    For our example we will figure 2 floors at 10 feet per floor.
    2 X 10 = 20 feet of head
    I dont think this applies to me as im in the basement

    Fourth step: figure the head loss in the 1-inch piping from the well to the pressure tank. This is assuming
    the pressure tank is in the house.
    For every 125 feet of 1-inch pipe there is 6 feet of head.
    For our example we will use 100 feet from the well to the house.
    100 divided 125 = .8
    8 X 6 = 4.8 feet.

    I am aprox 70 feet so I would get 3.4

    Fifth step: add all of the sums of the first four steps together.
    This total will give you the amount of head in feet the pump will need to overcome.

    Step (1) = 138.6 feet of head
    Step (2) = 180 feet of head
    Step (3) = 20 feet of head
    Step (4) = 4.8 feet of head
    138.6 + 180 + 20 + 4.8 = 343.

    My total would be 278.46 feet of head
    Pompco has a 3.4 hp 20 gal/min but my head appears to exceed the curve
    They also have a 3/4 hp 12 gal/min which would appear to fit nicely for this head pressure but im not sure if 12 gallons would be cutting it close. I could probably dial my geo down to 4.5 gal/min. What do you think?Am i interpreting the well info correctly or am I missing something
    Liam likes this.
  4. waterpirate

    waterpirate Well-Known Member Industry Professional Forum Leader

    That was complicated!
    You worked through their sizing sheet nicely, but some of thier basic info is sketchy. Your well info stated that at the conclusion of the pump test the static water level was 40 feet below ground surface. I assumed a pumping level based on 50 feet below surface. The pumping level in your well now pumping at a rate of 20gpm is the most important fact. The feet of head or pressure requirement needs to based on the pumping level in a well at a given rate.
    If the pumping level in your well is x, that is the feet of head number you need to work with even if the pump is set deeper. The depth of the pump below the pumping level is a wash. The weight of water in water is 0, it requires no head to pump it.
  5. LittleJohnny35

    LittleJohnny35 New Member

    Ok this makes more sense. So essentially in my case if my static level is 45 feet below ground level than my feet of head is 45 plus whatever I set my pressure tank as well as some friction loss from the well to my house (I will assume aprox 20). From this I would estimate my head to be between 157 to 203 depending if I set my cut out on my tank from 40 to 60 psi. This helps me get and idea of the range I have when trying to achieve the 20 gpm goal. Looking at the Pompco 3/4 hp 20 gallon curve i see those two feet of head readings fit nicely in the optimal section of the curve. This is perfect.....................now im going to go ahead and order the pump and control box and patiently wait for the winter to pass by and install the new pump. This should save me some big $$$ next winter as my geo runs a lot when it -20 c outside. Thanks a lot for your patience in explaining this to me.
  6. engineer

    engineer Well-Known Member Industry Professional Forum Leader

    Do you really need the full 60 psig?

    I run 30 on 42 off at ground level, and take perfectly acceptable showers, (indeed so vigorous that I always reduce the flow at the mixing valve) from a showerhead located 20' above the well pressure switch. I'm not one to abide wasting time waiting for a weak showerhead to rinse shampoo out of my hair.

    IMO Government-mandated fixture flow restrictors have had the unintended consequence of creating demand for unnecessarily high ("city") pressure in home water lines. That, coupled with abysmal efficiency (30-40% at best) of small water pumps constitutes a real hit on pumping power cost. It has the additional effect of rendering home water systems even more incompatible with open loop geo units needing only 3-5 psid across their heat exchangers.

    The EPA default shower head flowing 2.5 GPM does so at a ludicrous 80 psi

    The trick is to judiciously bore out or remove the restrictors. Note well I do not advocate water flows above EPA maximums; just elimination of the need for ridiculously high system pressures to achieve them. High pressures are expensive to maintain, increase wear and tear on fixtures, aggravate water hammer and exacerbate frequency and severity of leaks.

    Off-gridders, careful of every watt-hour, have identified domestic water pressure as an area of low hanging fruit for easy reduction. Careful selection and / or modification of plumbing fixtures allows comfortable, satisfying operation at pressures a small fraction of what is typical.

    OK, my beer is all gone, so I'll step off my soapbox and refill it.
  7. LittleJohnny35

    LittleJohnny35 New Member

    I agree with the lower psi. My goal once I put in the new pump is to try and run it between 20-40. I am specing out the total feet of head pressure using 40 as the min and 60 as the max. I will only set it higher than 40 if I need to in order to prevent my pump from cycling. Currently with my 1.5 hp well pump I have the cut in and out at 40-60 and I have roughly 12gpm going through the geo. I have to keep the cut out at 60 or increase the flow to the geo to avoid pump cycling. when i put in the new pump im going to shoot for 6gpm in the geo and see how high I have to set my cut out in order to keep the pump from cycling when geo is running.. Im thinking it will be under 50psi but if it has to be as high as 60 than I would prefer the higher pressure but avoid unnecessary cycling. Maybe I will have the numbers ust right and get both a proper gpm to the geo and a 20-40 pressure tank set-up. We will see
  8. waterpirate

    waterpirate Well-Known Member Industry Professional Forum Leader

    Before you order that pump a field verification of your current pumping level is called for. If you can not do it yourself, call a local well driller or plumber who can open your well and do it for you. Well log information as well as reports are notorious for being best guesses at best unless that info was in the contract upfront.
  9. engineer

    engineer Well-Known Member Industry Professional Forum Leader

    WP is right

    I'm far from an expert on wells but you have to know the actual level from which water is being pumped (not level where water sits with none being pumped) to have a hope of correctly specifying a pump
  10. LittleJohnny35

    LittleJohnny35 New Member

    makes sense

    Any recommendations as what to use to measure the water level during pumping?
    I know the well record I have shows a pump recovery test that was done for an hour period. I know this is not a long test but its what they did. The static level before the test was measured was 15.27 Meters (50.1 feet). After 5 minutes the level measured 15.78 meters (51.77feet) and stayed there for the rest of the hour. The level measured at the end of the hour was again 15.78 meters (51.77 feet). After 4 minutes the static level recovered back to 15.27 meters (50.1 feet). The pump rate for this test was 45 Liters/min (11.88 Gal/min) and the recommended pump rate was 45 Litres/Min (11.88Gal/Min). This was done aprox two years ago so im sure there is a chance these numbers have changed. I was thinking maybe I can use a fishing line with a bobber on it to get an idea of the level....bad idea? Anyways thats my thought process right now. Assuming these numbers are still relevant I think I should be good with the 3/4 HP pump.
  11. waterpirate

    waterpirate Well-Known Member Industry Professional Forum Leader

    Given the data if correct, While pumping the well at approximately 10 gpm, the differance between the static water level and the pumping level is approximately 2 feet.

    Specific capacity is expressed in gallons per foot of drawdown.

    Your well has a specific capacity of 5 gallons per foot.

    The 18gpm 3/4 hp pump would have a pumping level around 54 feet, the pump should be hung a minimum of ten feet below that or at 64 feet.

    We use a water level indicator. It has a probe that is lowered into the well past the pitless adapter and it beeps when it hits the water. If you are diy you can easily whip one up usinf some control wire and a 9 volt battery.
  12. LittleJohnny35

    LittleJohnny35 New Member

    Im not going to lie......that part I dont understand

    However, if the data given is correct and I verify my static level to be 15 meters below ground level can I hang my new pump at the same level of 45 meters below ground level as this would be 30 meters below static. I tried to understand how you got the 54 feet but for the life of my I cant figure it out.I apologize and appreciate all the help but this part im lost. Dont feel obligated to explain I just want to make sure if I hang the new pump at the same level as the 1.5 hp that it will be ok. thanks for all the info....maybe it will make more sense to me after I had a beer and watched some tv.....probably not though.:confused:
  13. engineer

    engineer Well-Known Member Industry Professional Forum Leader

    Makes sense to me - thanks WP for advancing my fund of knowledge by one notch
  14. waterpirate

    waterpirate Well-Known Member Industry Professional Forum Leader

    I am so happy I figured out my mistake before Urthboy showed up!lol:p
    I transposed feet and meters, Curt granted me some grace. Where I refer to 54 feet, please correct to 54 meters. Your well really has a specific capacity of about 20 gpm per meter. I was obviosly out drilling that day at school also.
    p.s. i promise to not delve into the realm of metric math again
  15. engineer

    engineer Well-Known Member Industry Professional Forum Leader

    Honestly, I didn't catch the metric transposition - I was just happy to leanr some ins and outs of well capacity and pump height.

    NASA made a metric / english error awhile back and it cost them a $200 Million Mars probe...OOPS!
  16. LittleJohnny35

    LittleJohnny35 New Member

    If the pump has to be hung at 64meters than Im kinda stuck. My wells total depth is 66meters and to be quite honest id rather keep the height to 45meters where it currently is so I dont have to extend piping etc. If the current 1.5 hp 20gpm pump is currently set at that height without issues couldnt I assume the 3/4 hp 20 gallon to be ok as well (assuming of course my head pressure is within range)??I would even consider getting a pump with less gpm like 15 if that makes a difference.

    sorry but one last question. I know I have a pitless adapter as I seen it when I opened my well last summer. I plan on making a tool with 1 inch piping to fasten to the adapter but the part im not sure about is whether i have a spring adapter or slot adapter. I am assuming its slot as I dont remember seeing any kind of cable that I could use to pull the latch for the spring. I read that some slot pitless adapters require loosening with a screwdriver or wrench before pulling the well out. How the heck could you reach down there with a screw driver or wrench???
  17. urthbuoy

    urthbuoy Well-Known Member Industry Professional Forum Leader

    Pitless adapter

    If someone couldn't reach down there to tighten it with a screw/wrench, it is unlikely that you have to reach down to loosen it.
    Last edited: Dec 20, 2010
  18. LittleJohnny35

    LittleJohnny35 New Member

    so what you are saying is i might have to go down there and loosen it?????

    Just kidding......good point BTW

    I guess im overthinking the well pump replacement thing. I just figured id try and cover all bases in my preparation. It seems every time I read something regarding the process....something new comes popes up. If the snow was gone I could do it now. instead im goinf to plan the sh&^^&%^5 out of it until spring comes.
  19. waterpirate

    waterpirate Well-Known Member Industry Professional Forum Leader

    Some pitless units require a key to open them. The key is mechanical in nature, either a thumb screw or a square head. The location of that device is on the pitless unit itself usually contained whithin a piece of one inch pipe so you can not see it. You need the right key, the right length to open the pitles. They were used here to prevent any service by anyone not the original installer. Paulus is one of the more deceptive ones.
  20. LittleJohnny35

    LittleJohnny35 New Member

    Thanks for the information Eric. I have decided after all this to get a guy to come in and replace the well pump now so that I can get it over with. I figure I can cover the extra cost for installation on the savings I will have over this winter with new pump. I have a question though...the installer is recommending I install a 3/4 Jacuzzi pump. I cant for the life of me find any info if this is a good quality pump. I know I dont have any speciifc regarding model but im wondering if you know if this is a good pump overall? Or is there something you would recommend. The guy wants to come out next Tuesday and install it so Im hoping to get some info as im a bit nervous that this pump wont be suited for a high usage geo system.

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