Getting less than 5 GPM

Discussion in 'Pumps and Tanks Well Forum & Blog' started by LLigetfa, Feb 6, 2011.

  1. LLigetfa

    LLigetfa DIYer, not in the trades

    Messages:
    3,967
    Location:
    NW Ontario, Canada
    I’m on well water that has a lot of iron and so have an iron filter. The downside of it is that the micronizer only works at lower pressures (higher flow rates) so the pump is set to come on at 25 PSI and shut off at 50. The micronizer stops sucking air at 40 PSI. The manual states that aeration should occur for 2/3 of the pump cycle.

    I have a Goulds 10GS05412 (1/2HP, 230V) in the well pumping from 50’ depth and I'm told I should get more than 10 GPM at 50 PSI but I don't. When I set the pump 12 years ago, the water table was 15 feet below ground. I don't know where the water table is now. As a test just now, I ran the pump until it reached 50 PSI and shut it off. Then I drew off 5 gal of water drawing down the storage and the PSI fell to 20. I turned the pump back on and timed how long it took to get back up to 50 PSI. It took 68 seconds, so that equates to less than 5 GPM through the micronizer.

    A little history on the well and pump... 12 years ago I had the mud well drilled through 50 feet of clay and hit a 5 foot layer of sand/gravel above the bedrock. The well was pumped for several days at 5GPM with the driller's pump. When I dropped in my 10 GPM pump, the additional flow rate caused the well to cave in and my pump ingested a lot of sand. The driller backwashed the well by dumping a few thousand gallons down it and then put some crushed stone down the well to hold back the sand. I got the pump unjammed but I think the sand caused some wear and that is why I cannot pull 10 GPM with it now.

    The iron filter is rated for 6 GPM service flow and I have measured and verified 6 GPM (drawing down storage) filling a 5 gal bucket. There is likely some pressure drop across the filter bed at higher flow rates but I have never tested the pressure. With the pump running, testing flow rate just before the iron filter I fill a 5 gal bucket in 30 seconds so that equates to 10 GPM but that's drawing down the storage as the pump cannot sustain that. That test was just to confirm that the flow to the filter is not restricted by iron build-up in the pipe which it does from time to time.

    From what I was told, the answer is to use a domestic water pressure booster pump. My water equipment supplier suggested the Grundfos MQ pump but from googling, most consider them junk and not intended for whole house boosting. It also won't increase the GPM of the Goulds so the PSI boost would only last until I draw down the storage. I don't think any booster after the storage is the solution.

    I've been looking at the Davey BF20-40. It purports to boost up to 63 PSI at 10 GPM with a 20 PSI head. If I connected it in tandem with the Goulds, before the micronizer would the flow sensor turn it on/off just once or would it rapid cycle and would it increase the GPM from the well? From what I can tell, the Goulds draws 5 amps running/6 amps starting. It is on a 15 amp breaker. The Davey start would be delayed from the Goulds but Davey recommends a 10 amp circuit. Anyone know how quiet or noisy the Davey is?

    Would I be better off with just an ordinary jet pump in tandem with the Goulds and slave it to the same pressure switch as the Goulds? They would both start at once so I would need to go to a 20 amp breaker. Maybe running two pumps in tandem is just a hair-brained idea... should I just replace the Goulds? How many more years can I expect to get out of it?

    Either way, I'm hoping to raise the kick-in and kick-out pressure between 10 and 20 PSI. What I'd really like is to have a constant pressure system but I just don't see how that's possible with the iron filter.
  2. valveman

    valveman Moderator Staff Member

    Messages:
    4,458
    Location:
    Lubbock, Texas
    I would check the flow from the pump at the well head. At 50’ that pump should deliver 16 GPM from a wide open pipe. Even if the well won’t make 16 GPM, the pump should still start out at 16 GPM, or iron maybe clogging the impellers.

    If the pump is OK and the well will produce 11 GPM, that pump should make 11 GPM at 50 PSI. If it doesn’t, then the micronizer or the pipe after the micrinizer is your restriction.

    You can use a CSV on the well. After the pump is running, the constant pressure will make the flow dependant on the amount being used. So if you are only using 2 or 3 GPM, the pump is only producing 2 or 3 GPM, which is not enough to make the micronizer work. Setting the CSV at 45 PSI while using a 30/50 pressure switch means the micronizer will work until the tank is ¾ full at 45 PSI, which is usually enough air to make the system work. Then the CSV will let the micronizer continue to work as long as you are using more than 5 GPM.

    Pumping from a non-pressurized storage tank is the best way to use a booster pump. Hook the well pump to a float switch in the storage tank. The well pump will keep the storage tank full of aerated, treated, and filtered water. Then a booster pump can draw as much water as you need from the storage tank, and deliver it at the pressure you want. In this way you can actually use a lot more GPM in the house than the well can produce, for short periods of time, depending on the size of storage tank. You can use a jet pump or a submersible from the storage tank as a booster. The submersible will be much more quite and give more GPM per horse power. You can use a CSV on either type pump, which will give you constant pressure and allow the booster pump to work with a very small (4.4 gallon) pressure tank.
  3. LLigetfa

    LLigetfa DIYer, not in the trades

    Messages:
    3,967
    Location:
    NW Ontario, Canada
    Ja, a non-pressurized storage tank is probably the best way to use a booster pump. Where to put one and how large to size it? I have a 4 foot crawlspace with limited access so I cannot drop a big tank down there. Mind you, I could daisychain a few smaller tanks.

    I'm guessing there should be as much or up to twice as much storage as the well casing has which would be around a gallon per foot, so 50 gallons in the casing and up to 100 gallons in the house.

    Come Summer, I should pull the pump, clean it and test the GPM. By my recollection, when I installed the pump 12 years ago, the micronizer still only worked to 40 PSI so at the time I set the pressure switch to 30/50. I doubt I can get the micronizer to work at 50-60 PSI with the existing 10 GPM pump to let me set the kick-out to 70-75 PSI.
  4. valveman

    valveman Moderator Staff Member

    Messages:
    4,458
    Location:
    Lubbock, Texas
    The faster your well can replenish the storage tank, the smaller the storage tank can be. If your well will replenish the storage tank at 5 GPM, and the most you ever use in the house is 10 GPM, then you are only using 5 GPM out of the storage tank. So a storage tank that holds 100 gallons can supply 10 GPM for 20 minutes, because the well is adding 5 GPM to the storage at the same time. If your well only made 1 GPM, you would need a bigger storage tank.

    Even so I would suggest as much storage as you can fit. 200 or 300 gallons should be more than enough.
  5. LLigetfa

    LLigetfa DIYer, not in the trades

    Messages:
    3,967
    Location:
    NW Ontario, Canada
    The idea of non-pressurized storage is making my head hurt. As my system currently stands, if I draw down the water table in the well, the pump needs to lift the water higher which reduces the GPM. Reducing GPM at the pump reduces GPM at the hose bib so it somewhat self-regulates. With a non-pressurized storage tank the GPM at the hose bib is not tied to the GPM from the well so there is a greater risk of running out of water. I can see where one would err on the side of caution and oversize the non-pressurized storage.

    Spending a couple grand on storage/booster won't get approval from the CFO. I may as well just upgrade the pump in the well with a higher GPM model that can keep the micronizer working to higher pressure. Only problem with pulling more GPM from the well is the risk of drawing it down too much and sucking in mud again.

    I've got one more hair-brain idea... apply a 20 PSI head of air to the micronizer air intake. That would give me 20 PSI more water pressure with air entrainment. I would need an oil-less air compressor with tank and regulator. If I install it in an out-building and pipe the air undergound with pex, the noise wouldn't be a problem. With enough air storage, I could have a timer on it so it cannot run at night.
  6. Gary Slusser

    Gary Slusser That's all folks!

    It sounds as if you don't have a pressure gauge installed at the pressure tank. And that you haven't taken the air venturi off to see if it and the pipe after it all the way to the inlet of the iron filter is blocked up (which it probably is).

    When is the last time you replaced the mineral in the iron filter, it may be blocked up and clumped etc.. If it is you have have rust blocking some of the filter's outlet pipe.

    Have you checked the captive air pressure in your pressure tank to be 1-2 psi less than the cut in setting of the pressure switch with no water in the pressure tank, if not you should.

    And as suggested, you must check the static water level in the well. And you should check the pump's open line output at the well by pulling the pump drop pipe up a few feet out of the casing and turning the power on to the pump.

    With high iron and/or IRB you could have the line from the well to the pressure tank blocked with rust.
  7. valveman

    valveman Moderator Staff Member

    Messages:
    4,458
    Location:
    Lubbock, Texas
    A bigger well pump is not going to help. You can only squirt so much through the micronizer no matter the size of pump. You can squirt even less through the micronizer if it or the pipe is plugged up. if you use the air compressor, you don't need the micronizer. The compressor may solve your low flow problem by itself. But hooking it up before the micronizer won't help.
  8. LLigetfa

    LLigetfa DIYer, not in the trades

    Messages:
    3,967
    Location:
    NW Ontario, Canada
    Gary,
    I have a pressure gauge after the micronizer, just inches before the air volume tank. I recently rebedded both the iron filter and the softener. I cleaned and inspected the micronizer at the time and frequently replace the air valve. I removed the sediment filter element and flushed the line from the well. The sediment filter traps black crud (manganese?) I cleaned out the lines between the sediment filter in front of the micronizer and the iron filter. I ran GPM tests without the sediment filter element to confirm it doesn't reduce GPM. I have a drain cock a foot before the iron filter and frequently flush the line and measure the GPM to ensure there is proper flow.

    The air volume tank is not a precharged bladder tank. I replaced the air volume control in the tank after it stuck, sending air to the iron filter during backwash, clogging up the valves. I cleaned out all the pumicite from the valve body of the iron filter.

    I realize there is a lot to read, but I detailed above, the flow rates at the different points in the system. I get less that 5 GPM from the well averaged over one pump cycle from 20 PSI to 50 PSI. I get 6 GPM after the iron filter and the softener. One foot before the iron filter at a drain cock, I get 10 GPM until I draw down the storage.

    One more test I can do is to remove the drain plug from the sediment prefilter and measure how long it takes to fill a 5 gallon bucket from a zero pressure start. That should rule out a clogged line from the well If I get similar results at the wellhead. It would also show the GPM before the micronizer restriction. The wellhead test I won't do until the snow is gone. Likewise measuring the static water level in the well.

    Please keep in mind that the micronizer stopped sucking air at 40 PSI since day 1 so I doubt the GPM has reduced over time. The pump injested sand on day 1. I thought I could test for impeller wear by seeing how much pressure the pump is capable of producing and I've taken up to 80 PSI. I'm afraid to take it any higher in case I burst a line or tank.
  9. LLigetfa

    LLigetfa DIYer, not in the trades

    Messages:
    3,967
    Location:
    NW Ontario, Canada
    In another thread you said that the flow rate determines to what PSI the micronizer will work. Would not a bigger pump put out more GPM? The dealer trying to sell me the Grundfos booster also wants to sell me a new micronizer and a new Grundfos submersible. He says he has a micronizer that will work to higher PSI but then he says a lot of things. He claims the Grundfos has stainless steel impellers and is more tolerant of sand and that the Goulds has plastic impellers which wear out.

    The Grundfos dealer is at odds with the Goulds dealer. When my well caved in with mud, the Grundfos dealer wanted to put an air hose down the well and blow the mud out. The Goulds dealer said that would just create a cavity making future cave-ins more likely. He proposed pushing the mud back by dumping a few thousand gallons down the well and then putting crushed stone down the well.
  10. LLigetfa

    LLigetfa DIYer, not in the trades

    Messages:
    3,967
    Location:
    NW Ontario, Canada
    My thought was to connect the air hose to the micronizer and then to back out the adjuster on the micronizer to allow more flow. If I can get more aeration at higher pressure (lower flow rates), I can then use a CSV for higher and constant pressure which is really what I want. The extra air should also help remove more of the Hydrogen Sulfide smell.
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