Bleed back question

Discussion in 'Pumps and Tanks Well Forum & Blog' started by dad, Oct 9, 2006.

  1. dad

    dad New Member

    Messages:
    3
    What would be a maximum distance from house to well casing for a bleedback setup? Also what pitch is necessary for this to function properly?
  2. Raucina

    Raucina Previous member

    Messages:
    515
    Bleedback for freezing or for charging a standard tank?

    Can't think of a length limit except for the waste of moving the water up and down.

    Length limit applies to tank air charging, you will get too much air.

    More grade the better, no traps and perhaps 1/8" per foot.
  3. Bill Arden

    Bill Arden Computer Programmer

    Messages:
    584
    Location:
    MN, USA
    I thought everyone used bladder tanks now days.

    But I would guess that for freezing you would need to maintain the same pitch as sewer line. More imortantly you must keep the pipe straight!

    Smaller pipe tends to have wavy or curved tendancys and thus you may have to tape it to something like a 2x4 before burrying it.

    The only distance limitation would be in how deep you want to dig to maintain pitch.
  4. Raucina

    Raucina Previous member

    Messages:
    515
    Standard tanks are indeed made and sold in America. Nothing inside to break, and a large standing water charge that greatly reduces freezing issues in medium climates. [Bladder tanks can draw down to near empty and stand there and thus freeze] Dollars per gallon of water stored is much lower than with bladders and standard tanks dont blow masses of gunk into the house as when bladders break. I think they would be better called "Colon tanks" to best reflect what happens when they fail and what enters your pipestream.

    S-it happens and that's what is behind the bladder. I would guess the well guys make more on the bladder tanks and they can handle less bulk and weight on an install for a given drawdown. I use some too, but only if space does not permit.

    If anyone wants one, sears has them at a great price and free delivery to the catalogue stores. They appear to made by AO smith.
  5. Bob NH

    Bob NH In the Trades

    Messages:
    3,317
    Location:
    New Hampshire
    Standard tanks are indeed made and sold in America.

    The next post will probably be along the line that "Homeowners are neither intelligent enough nor diligient enough to manage the air in a standard non-bladder tank."

    The reality is that with proper management of the system, a non-bladder tank can have virtually the same drawdown capacity as a bladder tank of the same physical size.
  6. Phil H2

    Phil H2 New Member

    Messages:
    125
    Location:
    Tujunga, CA
    Bob,
    How does that work? I thought the non-bladder tank had zero air pressure when the pump is shut-down and the water is bled. If that is the case, 50% of the tank volume would be consumed when pressurizing from 0 - 15psi (Ideal Gas Law / Boyle's Law). Perhaps, I am mistaken about how non-bladder tanks work.
    Phil
    Last edited: Oct 11, 2006
  7. Bob NH

    Bob NH In the Trades

    Messages:
    3,317
    Location:
    New Hampshire
    "How does that work? I thought the non-bladder tank had zero air pressure when the pump is shut-down and the water is bled."

    A non-bladder tank can be precharged with air to 2 psi less than the ON setting of the pressure switch. You should make the water connection to the tank at the drain level, just as is done with a bladder tank. Empty the tank to that level; close the discharge valve; and pressurize to the desired pressure. Then run the pump to shutoff pressure before you try to use any water.

    Maintaining the tank is even easier. You need a means of determining the water level; either a sight glass tube, or by observation of the sweating tank, or by tapping on the tank. The level of water in a tank corresponds to an air pressure for a correctly charged tank.

    For a 30/50 tank, using the practice of 2 psi less than the switch setting when empty, the pressure when empty of water will be 28 psig = 43 psia (at sea level). That is also the point where the tank is full of air (100% air).

    psig = psi gauge (what you meaure)

    psia = psi absolute = psig + atmospheric pressure

    Now when the tank shuts off at 50 psig (65 psia), the volume of air in the tank will be 43 psia/65 psia = 0.66 = 66%.

    So when the pump shuts off at 50 psig, the water should be at the 34% level.

    To maintain the air charge when there is too much water, run the water down to the 34% level and add air to 50 psig.

    So here are the water levels for a 30/50 tank with 28 psig at empty:

    0% 28 psig
    5% 30 psig
    10% 33 psig
    15% 36 psig
    20% 39 psig
    25% 42 psig
    30% 46 psig
    35% 51 psig

    Now you can observe the level at any time and adjust the air pressure to get the correct air in the tank. If it is above 35%, you should let some water out of the tank to the 35% level and pressurize to 51 psig.
  8. dad

    dad New Member

    Messages:
    3
    Sorry, a few days got away from me. I'm in NY. The bleedback would be to prevent freezing as the original installation done some 20 plus years ago is only 17" below ground at the pitless. I cannot lower the pitless because there is solid rock for most of the yard. I have converted several bladder systems to bleedback after the original heat tape failed. This one is just a bit further from the house (40 ft.) than I have had prior experience with.

    Any sound advice is appreciated. If you can refer me to tank or pump manufacturer literature on the subject, even better.

    As for installing a bladderless tank without a bleedback and AVC, this is something I would never do. I am paid to give my customers as maintenance free a system as possible. I seems absurd to expect them to have to own a compressor because I think they're smart enough to use it.
  9. Bill Arden

    Bill Arden Computer Programmer

    Messages:
    584
    Location:
    MN, USA
    17 inches... I have to keep stuff below 6 feet here.

    I would suggest you use Styrofoam over the pipe if you are re-digging it anyway.
    Just lay it over the pipe horizontally so that the frost has to go around the edge and then back in towards the pipe.

    Here we use 2-inch thick and 4-feet wide (each side) yellow foam to deal with the 6-foot frost line, but with your lower frost depth, you could use thinner and narrower foam.
  10. Raucina

    Raucina Previous member

    Messages:
    515
    Welcome back Mr. NH, and thank you for the standard tank information and confirmation.

    One can tee in a clear high pressure vinyl hose from the top gauge port to the lower inlet easily and have a sight gauge; Had not thought to try it until now and would make the air issue homeowner friendly. Useful with or without a precharge. The sears tanks have 2] 1.25" ports down low on the tank so one could still use the ARV with a precharge by plugging the intermediate port. [actually we discussed methods of precharge by compressor at length in previous posts] I think the ones I buy are 120 gallon, but since they are made in a water heater factory [glass lined] I suppose they meet gov. spec.

    One need not start the precharge in the standard tank with the tank empty. I dont have figures but I start my precharge with the tank about half full and still get a very large increase in drawdown.

    One issue of interest is the adsorbtion rate of the air charge into the water. Is there a formula for surface area/ pressure that would predict the interval between charges? Older tanks had a floating disk that reduced that to a bare minimum.

    As to the drain down issue, one can always test the bleeder valve under pressure - I have never seen a spec for the maximum pressure before the leakage stops. Its not a big leap to take a file and make a defect in the seating are to insure that the leak never stops no matter the pressure in either a rubber or brass valve... at the cost of efficiency.

    If one had 40 feet of say 1.5" pipe and a drain down valve, I think he would exceed the capacity of the ARV and thus get air into the system.

    I gave up the 6' frost line for the 6" one years ago and never looked back. Still get 4 seasons here in the Sierra foothills but without the suffering. Every 5 or so years everyones pipes freeze solid but typically only the copper and pvc break.

    Since so many sell stuff here can I put in a link to my land for sale as long as it includes a well and a rent a hubbie to keep it running?
    Last edited: Oct 11, 2006
  11. dad

    dad New Member

    Messages:
    3
    Well, thanks to everyone for all the advice, BUT it's all moot now. I went up to the house today and looked over a few things and this time when I popped the well cap off the water was up over the pitless (17" below the surface) and even a few inces above ground level!
    I'm glad I was able to observe this condition BEFORE converting to a bleedback! I guess their stuck w/ heat tape and/or styrofam.

    I still get to convert the scorched air heat to hot water, so I'm happy.
    Funny thing is this house used to belong to a plumber- you should see the dips and valleys in the drain system!!!

    Thanks again.
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