adding additional 50-100 gallons of pressurized storage to shallow well system

Discussion in 'Pumps and Tanks Well Forum & Blog' started by lpnd, Aug 1, 2013.

  1. lpnd

    lpnd New Member

    Messages:
    2
    Location:
    ND
    I've read around the forum about adding large non-pressurized storage tanks for low yield wells, but I don't have the space for either an above ground or buried large volume storage tank. Furthermore, we don't use much water at our cabin and having 50-100 extra gallons would be adequate for our weekends. We are going to try nu-well tablets to clear our sand point and increase the yield (we get about .5 gpm currently) but I am also wondering if i could add an air-over pressure tank after the pre-charged pressure tank and only use the conventional tank strictly as storage (no air-volume controller, just water in and water out). I considered adding a larger pre-charged tank, but the existing tank is 44 gallons and adding a second conventional tank would take up considerably less space while offering more water storage. Would adding this second pressurized tank for storage work or do i need to look at a non-pressurized tank and two pump setup?

    Thanks for your help/advise!

    Luke
  2. Texas Wellman

    Texas Wellman In the Trades

    Messages:
    523
    Location:
    SE Texas-Coastal
    Yes. Just make sure you keep the air head in the 2nd tank up every few months. With the main tank being a bladder tank it makes for a very nice set-up.
  3. valveman

    valveman Moderator Staff Member

    Messages:
    4,426
    Location:
    Lubbock, Texas
    It would be like having a 20’ long section of 12” pipe coming into the house. Sure it has 100 gallons of water in it when full, but there is nothing to push the water to the house. In a pressurized system, air works like a spring to push the water from the tank to the house. But the tank has to have about 75% air to do this. That is why your 44gallon tank only holds 12 gallons of water.

    You could make it work by adding a compressor to the “storage” tank. You would have to run the compressor on a lower setting pressure switch than the well pump. You would also need to work out the vent/vac system that would allow the “storage” tank to fill (vent), and then close off when the compressor is pushing the air out of the tank. Then you need level controls for the pump filling the storage tank, and a Dry Well protector/timer like the Cycle Sensor, etc., etc.. Not really a feasible option as you can see.

    The best you can do is to “pre-charge” the non-bladder style tank with an air compressor, and widen the bandwidth of the on/off of the pressure switch as much as you can. Sounds funny but, the more air in the tank, the more water it can push to the house. I would pre-charge the bladderless tank to about 28 PSI with air, then set my pressure switch to turn the pump on at 60 and off at 70, if the pump can build that much pressure. That would give you the most “draw-down” from a pressurized tank. That should get you about 50 gallons of pressurized water from a 100gallon size tank, as the pressure decreases from 70 PSI to 30 PSI. The 60/70 pressure switch setting would help keep the tank “topped off” as much as possible. But with such a low producing well, the pressure will continue to drop to 30 or so as a Cycle Senor or some kind of Dry Well relay turns the pump on and off according to how much water is in the well.

    Also the lower the pressure you can live with in the house, the more water the tank will actually hold. In other words it would store more water working from 10 to 50 PSI (using a 40/50 switch), than it would working from 30 to 70 PSI (with the 60/70 switch). But you could have pressure as low as 10 PSI in the house with the lower setting.

    Are you sure you don’t have room for a vented storage tank and a booster pump? :)
  4. valveman

    valveman Moderator Staff Member

    Messages:
    4,426
    Location:
    Lubbock, Texas
    With a 30/50 switch this would give you about 30 gallons form the 100 gallon tank. That might be enough, but you can’t store 100 gallons in that 100 gallon tank unless it is vented. Didn't mean to step on you TW. As you can tell from my long windedness I was typing. :)
  5. Texas Wellman

    Texas Wellman In the Trades

    Messages:
    523
    Location:
    SE Texas-Coastal
    A regular galv. hydropneumatic tank has about a 10% draw down. In other words, a 82-gallon tank has about a 8 gallon draw down and a 120 gallon tank has about a 12 gallon draw down.

    If you give that tank a pre-charge by adding compressed air you can increase the "draw down" to about 50%.

    I put draw down in quotes because it's not the std. 30-50 or 40-60 that you can get with a pump pressure switch and a bladder tank.

    A bladder tank will push out water at full pressure all the way up until it is empty, whereas a galv. tank with an air charge will push water out until there is either no more air pressure or no more water. So if you have a 120 gallon galv. tank you could very easily draw 50 gallons out of that tank, albeit at a reduced pressure once you get past the normal draw. My chart shows me that a 120 gallon galv. tank with a pre-charge has a drawdown of 37 gallons at a pressure switch setting of 30-50. But the tank will continue to let water out well past that 30 psig, it will just not be at full pressure.

    I stand by my statement Valveman and I do think that the twin set-up of a bladder tank with a galv. tank would work quite well, although I did need to qualify what I meant and also I do not think you would get 100 gallons of storage, but 50 or so gallons is within reach.

    Last edited: Aug 5, 2013
  6. LLigetfa

    LLigetfa DIYer, not in the trades

    Messages:
    3,920
    Location:
    NW Ontario, Canada
    The following statement may lead one to think the OP did not plan to charge the tank with air.

    If a hydro-pneumatic tank is supercharged so that it is essentially empty at the kick-in setting, drawing more water than the well can make will eventually result in losing the air out the faucet, perhaps knocking a glass out of your hand. At least with a bladder tank, the air stays in the tank.

    If it is not supercharged then yes, more gallons are available at a much (diminishing) lower pressure.

    Personally, I would remediate the well or punch down a new one.
  7. valveman

    valveman Moderator Staff Member

    Messages:
    4,426
    Location:
    Lubbock, Texas
    I am not arguing with you TW. I think I said the same thing above. Although with only a .5 GPM well, you would want to keep the tank "topped off" as much as possible and not let it drop to low pressure until you need to use the stored water.
  8. Texas Wellman

    Texas Wellman In the Trades

    Messages:
    523
    Location:
    SE Texas-Coastal
    No worries. I think we both agree. I must've missed the last part of your post.
  9. lpnd

    lpnd New Member

    Messages:
    2
    Location:
    ND
    I continue to appreciate the feedback from everyone. Over the weekend we used nu-well tablets to clean out the sand point. We are up to 2 gpm (up from .5 gpm). While still fairly low yield, this is a huge gain for us and probably as good as it will get from a shallow well in our area. I measured the well and it's only 20' deep, so adding depth might be an option i consider this fall or next spring.

    @LLigetfa- I should have been more clear, but you are correct, i was hoping/anticipating adding the second tank without adding any additional air pressure to it, just attempting to push it's stored water with the pressure from the first (44 gallon bladder style) tank. Forgive my poor drawing skills: photo.jpg Also, a new well may be on the list, but installing a second tank is cheaper and easier for me to experiment with first if i understand what valveman and Texas Wellan are saying...

    From what i understand, my proposed configuration could increase water storage but at lower pressure and at best 50% of the tank volume. Is this summary correct?

    Now that the well is "gushing" at 2 gpm :D, could i pose a follow up question: If I don't mess with adding a second tank and stick with the existing pump and precharged bladder tank, is it feasible to adjust the pressure switch so that the pump cuts in at say 35-40 psi instead of the standard 30 psi (30/50 switch) while keeping the bladder tank pressure at 28 psi? I'd think this adjustment would allow us to keep more water in the system, provided we draw around 2gpm somewhat consistently (for example running the shower). In a higher yield well i could see how this could cause the pump to short cycle, but in my situation I'd think it would shorten run time and provide more consistent water and pressure before the tank storage is depleted.

    Again, I sincerely appreciate you all taking the time to answer!

    -Luke
  10. LLigetfa

    LLigetfa DIYer, not in the trades

    Messages:
    3,920
    Location:
    NW Ontario, Canada
    Without air, that would not give you any additional usable storage. To get a gallon of water out of the second tank, you need to put a gallon in the other end.
  11. valveman

    valveman Moderator Staff Member

    Messages:
    4,426
    Location:
    Lubbock, Texas
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