Greenhouse irrigation/Amtrol tank

Discussion in 'Pumps and Tanks Well Forum & Blog' started by theplayer11, Sep 7, 2013.

  1. theplayer11

    theplayer11 New Member

    Messages:
    7
    Location:
    Rhode Island
    Hi all,

    I have a question about greenhouse irrigation. I currently have a 180 foot well with submersible pump with Amtrol tank..prob about 25-30g tank This tank is about 10-12 years old and has never had air adjusted. I irrigate for up to 6 hours a day sometimes, regular garden hoses, about 200 feet long for my greenhouses. I'm confused about why I even need a pressurized tank. Since the sub pump isn't cycling, it just turns on and runs constant until I stop watering. Question: Is the Amtrol tank increasing my PSI at all? I have noticed a drop in pressure when watering and I believe that is do to the sub pump wearing out and or getting slowly clogged with rust over the years(lots of rust in my area).....or could this have something to do with the Amtrol tank? My pressure gauge is broken, but I believe after the tank is run down, the pressure gauge used to drop to zero....does that make sense? Any suggestions on a replacement tank if pressurized tank is not needed?

    I should add that most of the time, I'm watering off a booster pump being gravity fed from a 1500g storage tank. I have this storage tank filling from the sub pump to Amtrol tank. I also fill this tank over night and have noticed that it is taking longer and longer to fill this storage tank. Again, this would be a submersible pump issue and not the Amtrol tank...right?
  2. craigpump

    craigpump Member

    Messages:
    944
    Location:
    ct
    Tanks do not make pressure, the pump does. The tank acts a pump control device which prevents the pump from cycling on and off while water is being used. The bigger the tank, the less often the pump cycles.

    If you have a loss of pressure, most likely the pump is wearing, there is a compromise in the piping someplace or possibly the well yield is decreasing.
  3. theplayer11

    theplayer11 New Member

    Messages:
    7
    Location:
    Rhode Island
    thanks for the response...had another reply post, not sure what happened, must have vanished. Anyway, current Amtrol is 15 years old, psi at 35, bladder seems OK, not water logged..bit of surface rust and some rust at the bottom underside since it's in a greenhouse under poly, but high humidity. Would you recommend maybe a fiberglass/plastic tank for my purposes?...Also, current tank is wx-302, do I need such a big tank since cycling is not a problem for me as once the pump starts, it doesn't stop until 4-6 hours later when I'm done watering. I'm thinking maybe the smallest tank possible?
  4. valveman

    valveman Moderator Staff Member

    Messages:
    4,468
    Location:
    Lubbock, Texas
    This is true, but a pressure tank does not “prevent” cycling. The bigger the tank, the less the pump cycles, but a pressure tank does not prevent cycling.

    Either your pump is worn down or there is a hole in the drop pipe. When you get this fixed, the pump will cycle on/off while running a hose, no matter how large a pressure tank you have.

    Without a Cycle Stop Valve you need as large a tank as you can get to limit the cycling. With a CSV you can use as small as a 4.5 gallon tank, because the CSV does “prevent” cycling completely as long as you are using more than 1 GPM.
  5. theplayer11

    theplayer11 New Member

    Messages:
    7
    Location:
    Rhode Island
    I'm not following..when I'm watering, the pressure is always well below the cut in pressure(If not zero), so wouldn't the well pump always be running?..I've never noticed the
    pump cycle off at any time when I'm watering or when my 1500g storage tank is being filled. The Amtrol tank runs down in about 2 minutes and from that point on, I believe the well pump is constantly running. Is this not [possible? I'm usually watering with 200-250 foot hoses.
  6. valveman

    valveman Moderator Staff Member

    Messages:
    4,468
    Location:
    Lubbock, Texas
    It depends on how large the pump is. Is the pump big enough to run 1,2,3, or more hoses at the same time? If you only run 1 hose at a time does the pressure increase? If not, then I still think you have a hole in the pipe or the pump could be worn out.

    With a pressure switch controlling the system, the pump should be cycling on and off for sure if you are only running one hose. And is probably a large enough pump to be cycling when using more than 1 hose. If it only takes 2 minutes to empty a 32 gallon tank of its 8 gallons of water, then you are only using 4 GPM, and the pump should be cycling like crazy. The pressure should certainly not be low or zero, so either the pump is not even putting out 4 GPM or you have a leak.
  7. theplayer11

    theplayer11 New Member

    Messages:
    7
    Location:
    Rhode Island
    the WX-302 Amtrol tank is 86g according to their site. I'm currently getting 5GPM coming up from the well pump and I know this used to be more, so yes, i'm quite sure the pump is faltering or slowly getting clogged with rust. Once the Amtrol tank is drawn down after a few minutes and I hear the switch click on, the pressure drops off dramatically to about 5GPM. But since the pump is rated at 7GPM, depending on the total head, wouldn't 5GPM not be unusual? 5GPM coming through 200 feet of garden hose is not a lot of pressure to water with.

    I'm still confused as to why there should be more PSI if only 5GPM is coming from the well pump. If I opened the faucet from the Amtrol tank wide open, after the tank is drawn down and the well pump turns on...wouldn't that water being pumped up from the well go straight out the Amtrol faucet with very little PSI? I guess what I'm asking is, what would build the PSI? The tank isn't doing any pressurizing as the water is coming straight from the well piping and out the Amtrol tank faucet when opened....right?..or does it go into the tank? ... or would it mater where the faucets are placed?
    I have 2 faucets in line, one before the piping to the tank and one after.
  8. valveman

    valveman Moderator Staff Member

    Messages:
    4,468
    Location:
    Lubbock, Texas
    Pressure tanks don’t pressurize anything. They simply store any extra water produced over what you are already using. So if your pump only produces 5 GPM, and you are using 6 GPM, the tank isn’t getting any water and the pressure keeps dropping to almost zero. It doesn’t matter where the faucets are, it only matters how much they are letting out. If the faucets are opened to 4 GPM, then the 5 GPM pump will keep the pressure up and the tank will fill to 60 and the pump will be shut off.

    But if the faucets are letting out more than the pump can produce, the pressure will drop really low. The main problem is that you are using more than the pump is delivering, so the pressure drops to nothing. Either you are just using too much water, the pump isn’t producing as much as it should, or you have a hole in the drop pipe.
  9. theplayer11

    theplayer11 New Member

    Messages:
    7
    Location:
    Rhode Island
    that makes a lot of sense, you've been great..so, with faucet wide open on Amtrol tank and pump only producing 5GPM, it makes sense that the PSI on the pressure gauge drops to zero..right?
    That is what is currently happening. So my next dumb question would be, how many GPM come out of a wide open faucet....I assume it would depend on how many GPM the pump is producing, but at what point would the Amtrol tank start filling with water? What if the pump was producing 10GPM?
  10. valveman

    valveman Moderator Staff Member

    Messages:
    4,468
    Location:
    Lubbock, Texas
    Depends on the faucet. Some will only put out 2 GPM while others will put out 40 GPM.

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