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Thread: Pump not drawing/won't prime

  1. #1
    Join Date
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    Default Pump not drawing/won't prime

    We are getting a new liner for our pool, but it has been delayed due to incessant rain. It rains for a few days, then stops for a day or two... then rains again. We have had 9 " so far in May. As a result, the water table is too high to get the liner installed right now. Sooooo... I haven't put much thought into the pool until a few days ago. It is at this point that my sad tale begins...

    When I pulled the cover off, the water was pond-ish green, scummy, looking. I closed the pool as per our pool store directions, but still had awful water. I drained all lines and capped them, (i.e. the 2 return jets, 2 skimmer ports with homemade plugs) I missed the main drain... forgot to plug it.

    We wanted to paint the coping before the new liner was installed, so I thought I would try to get the pump running so I could drain off a couple of inches so I wouldn't be face to face with the mucky water and tadpoles and such. When I went out to the pump/filter area, I noticed that the pipes on one of the skimmer lines were broken/busted. I repaired them. I actually replumbed the suction side pipes for both skimmers and the main drain. I can't get the pump to draw water. Not on either skimmer line, or the main drain, or the all three together. I read somewhere in these forums that the lines might be plugged so I bought a drain clean bladder and flushed the lines out for 10-30 minutes each. Still no draw. Here is what I am trying...

    1. close all valves on suction side
    2. remove pump basket lid
    3. fill with water until it holds no more water.
    4. replace pump basket lid
    5. slowly open valve
    6. wait 30-60 seconds to see if it draws
    7. If not repeat.

    Note: When I turn on the pump the water in the basket is sucked down rapidly.

    Before I tried this procedure I had closed all valves but one, then let the pump suck on that line for 30 minutes and got no results.

    Any suggestions?
    Do I have a leak on my suction side?
    How can I determine if I have a leak and where?
    I have no soggy ground anywhere along the path of the pipes from the pool to the pump system, so I don't think I have a leak underground.

    Help!

    BTW... Once I get this running again, it runs 12 months a year... I am not opening a cement pond again! I'd rather pay to run it all year.

    Ed
    Thanks,
    Ed

    --------------------------
    33,000 Gallon
    20'x40'
    Vinyl
    IG
    --------------------------

  2. #2
    Poconos is offline SuperMod Emeritus Sniggle Mechanic Poconos 4 stars Poconos 4 stars Poconos 4 stars Poconos 4 stars Poconos 4 stars Poconos 4 stars
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    Default Re: Pump not drawing/won't prime

    Hi Ed,
    You probably do have a suction side leak somewhere. All it takes is a very tiny leak to let enough air in to prevent the pump from self priming. The design of the pump, with the very small clearance between the impeller and housing, will create a very small vacuum that is usually enough to raise water a couple feet if your lucky, and start water flowing. These things are designed to be fluid pumps, not air pumps. When you fill the basket and fire the pump, dumping that water and emptying the basket is normal. To get the thing going you may try sticking a garden hose in one of the skimmer lines and stuffing a rag or something around it for a seal, then opening the valve to that one skimmer only. Fire the pump and turn on the water. This will force a constant supply of water on the suction side and should get the thing going. Then pull out the hose but don't let the rag get sucked in. If you have an air leak you'll see bubbles coming out the returns. Then slowly start opening the other return line valves and see what happens. Something else to try is if you have a multiport valve and can bypass the filter, try that. This should lower the resistance on the pressure side and assist in the priming process. Let us know what happens and we'll go from there.
    Hope this helps.
    Al

  3. #3
    Join Date
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    Default Re: Pump not drawing/won't prime

    That was a Brilliant idea! Took about 5 minutes to get it going and that includes walking to the street to connect the hose, connect the drain bladder and everything! The frogs are not happy though... as soon as the return line started flowing and the water and bubbles poured out there was an exodus of frogs jumping out of the pool.... "Oh crap... the pump and filter working!"

    One last question though... I haven't noticed any bubbles in the return jet output... If I do have a small leak, can I live with it if the pump is drawing water?

    Once again... Brilliant!

    Thanks,
    Ed

    Quote Originally Posted by Poconos View Post
    Hi Ed,
    You probably do have a suction side leak somewhere. All it takes is a very tiny leak to let enough air in to prevent the pump from self priming. The design of the pump, with the very small clearance between the impeller and housing, will create a very small vacuum that is usually enough to raise water a couple feet if your lucky, and start water flowing. These things are designed to be fluid pumps, not air pumps. When you fill the basket and fire the pump, dumping that water and emptying the basket is normal. To get the thing going you may try sticking a garden hose in one of the skimmer lines and stuffing a rag or something around it for a seal, then opening the valve to that one skimmer only. Fire the pump and turn on the water. This will force a constant supply of water on the suction side and should get the thing going. Then pull out the hose but don't let the rag get sucked in. If you have an air leak you'll see bubbles coming out the returns. Then slowly start opening the other return line valves and see what happens. Something else to try is if you have a multiport valve and can bypass the filter, try that. This should lower the resistance on the pressure side and assist in the priming process. Let us know what happens and we'll go from there.
    Hope this helps.
    Al
    Thanks,
    Ed

    --------------------------
    33,000 Gallon
    20'x40'
    Vinyl
    IG
    --------------------------

  4. #4
    Poconos is offline SuperMod Emeritus Sniggle Mechanic Poconos 4 stars Poconos 4 stars Poconos 4 stars Poconos 4 stars Poconos 4 stars Poconos 4 stars
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    Default Re: Pump not drawing/won't prime

    Happy to hear you got it working. As for living with it, depends on where the leak would be located. A tiny leak on the suction side and subsequent bubbles, but you have none, is no big deal. Where it becomes a problem is if the pump basket drains out when it's off and won't prime when you kick it on. Could it have been something as simple as a small piece of crud on the pump basket seal? Clean it and lube it with silicone grease available at pool stores. That stuff won't attack the gasket materiel. Also curious how far above the water level the pump is located. Some installations may actually take a minute or so before the pump is able to start pumping water.
    Again, good show.
    Al

  5. #5
    Join Date
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    Default Re: Pump not drawing/won't prime

    Ok... I spoke too soon and jinxed my work...

    Yesterday the pump ran good for 3 or 4 hours then slowly began to pump less water, eventually producing bubbles and finally stopping. I guess that means I have a leak?

    This morning, I tried to restart the flow as I did yesterday and while at the pump I saw what appeared to be a drip coming from the connection between the pump and the pipe(s) going TO the filter. Is this still the suction side, or since it is on the top of the impeller housing going to the filter, would it be the pressure(?) side? Could this be causing my problems?

    Two years ago, I moved the filter and pump system. It was 3 or 4 feet from the pool and wanted to move it out further away out of site. As a result, it is now maybe 1 foot higher than before. Additionally, the pipes look like something in Rube Goldberg setup, not my best effort. I am considering replumbing the entire suction side of things to remove as many turns as I can because I read in a pool maintenance book that the more turns in the pipes, the more suction pressure required to pull the water. Is this a good idea? Also, I have all my joints glued, effectively creating one big mass of pipes, filter and pump. Any movement in one pipe, the pump or the filter, would, I guess put pressure on other joints down the line. Are there PVC joints, or connections, I can to, in effect, isolate the pump and the filter, and the multiport valve? My thinking is that by doing so, any pressure used to change the multiport setting, or take the lid off the pump basket, would be isolated from other joints. Lastly, should I paint my pipes to protect them from UV?

    Ed




    Quote Originally Posted by Poconos View Post
    Happy to hear you got it working. As for living with it, depends on where the leak would be located. A tiny leak on the suction side and subsequent bubbles, but you have none, is no big deal. Where it becomes a problem is if the pump basket drains out when it's off and won't prime when you kick it on. Could it have been something as simple as a small piece of crud on the pump basket seal? Clean it and lube it with silicone grease available at pool stores. That stuff won't attack the gasket materiel. Also curious how far above the water level the pump is located. Some installations may actually take a minute or so before the pump is able to start pumping water.
    Again, good show.
    Al
    Thanks,
    Ed

    --------------------------
    33,000 Gallon
    20'x40'
    Vinyl
    IG
    --------------------------

  6. #6
    aylad is offline SuperMod Emeritus Vortex Adjuster aylad 4 stars aylad 4 stars aylad 4 stars aylad 4 stars aylad 4 stars aylad 4 stars
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    Default Re: Pump not drawing/won't prime

    Don't know about all the plumbing, but one thing to check is the spider gasket in the multiport valve. Mine has to be replaced every couple of years because it gets all crumpled up, and when it does that, I get a very small air leak that I only notice when the pump is off for more than 12 hours or so, but it does drain my pump basket after about 12 hours. I don't notice the leak at all when the pump is on. It's a pretty quick fix with a $12 gasket. It would be worth checking.

    Janet

  7. #7
    Poconos is offline SuperMod Emeritus Sniggle Mechanic Poconos 4 stars Poconos 4 stars Poconos 4 stars Poconos 4 stars Poconos 4 stars Poconos 4 stars
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    Default Re: Pump not drawing/won't prime

    Ed,
    That drip you mention is on the pressure side. Won't affect the suction or the ability to prime but it could be the reason the water drains out when the pump is off. In any plumbing situation the fewer bends the better. Each change in direction adds more flow resistance whether it be on the pressure or suction side. The number of bends on either side won't affect the ability to self prime, only add more resistance to flow once water starts flowing. As for isolating things when you replumb you have two options. You can add Unions which allow you to disconnect components but they do nothing to reduce noise and physical stress on components. My solution was to use straight sections of auto radiator hose to connect PVC sections. Nice thing is they allow for some movement between parts and the hose does hold up real well. I've been using the same hoses for years now and are just starting to show some deterioration on the inside but should get several more years out of them. Radiator hose is reinforced and designed for high temperature and adequately high pressure and the pool environment is very easy on them. Ypu can get 3 foot straight sections in various diameters at any good auto store. Buy the cheapest you can. Some are super thick and overkill for this application.
    Here's a couple past threads with some pics. In the one you can sort of see the other hose sections behind the filter.

    http://www.poolforum.com/pf2/showthread.php?t=6156
    http://www.poolforum.com/pf2/showthread.php?t=7054

    Al
    Last edited by Poconos; 05-27-2009 at 08:35 AM.

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