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Thread: pump losing prime - did I miss anything obvious

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    pump losing prime - did I miss anything obvious

    Ok, so my pump has been losing prime for a while, but it started to get really bad a couple months ago. Since then I have fixed a few obvious pump area leaks: gasket on junk catcher basket (+lubed), spider gasket on multi-port, o-rings on the two three way jandy valves, the run of 2" PVC pipe connecting the pump outflow to the multiport (there was a small drip).

    After I was done the new PVC run, I noticed something I should have observed earlier. Take a look at the image, the jandy on the far right connects to the skimmers (far side) and bottom of pool (close side). The jandy to the left of that brings in the return from a slightly elevated spa.

    When the flow to the pump is only coming from the spa and then I shut off the pump no air gets into the system. When the pump is on and I switch the flow back to the pool returns I get a reasonable amount of air. If I turn the jandy on the far right to bottom of the pool only I get more air, when I turn it to the skimmer returns I get air, but a bit less.

    So at this point, did I miss anything obvious? It seems to me I have a suction side leak somewhere on both of those returns. Appreciate any insight.
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    Re: pump losing prime - did I miss anything obvious

    The jandy valves and especially the piping going into the pump look improperly installed. Are they all glued or are they threaded?
    Dave S.
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
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    Re: pump losing prime - did I miss anything obvious

    Quote Originally Posted by duraleigh
    The jandy valves and especially the piping going into the pump look improperly installed. Are they all glued or are they threaded?
    The Jandy valves are glued. When I took apart the Jandy valves it looks like they said 1993 on the inside. The pool is at least 30 years old. I bought the house just over a year ago.

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    Re: pump losing prime - did I miss anything obvious

    Glued pvc fixtures should not touch each other like yours do. There is a decent chance the pipes in between all/some of those joints never seated properly and are sucking some air. The pipe into the pump on the suction side is also noticeably crooked.....another "no no".

    If you are intent on stopping your suctions side leaks, I would redo that entire side by cutting it loose at the pump and cutting all the pipes at ground level and installing all new correctly.

    If you are not familiar with PVC, a good service tech should be able to do that in a few hours + 2 new Jandy valves.

    I would also install a union or 1/2 union in front of the pump so you can simply unscrew the pump if it needs repair/replace in the future
    Dave S.
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
    TFTestkits , PoolMath , Pool School

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    Re: pump losing prime - did I miss anything obvious

    Quote Originally Posted by duraleigh
    Glued pvc fixtures should not touch each other like yours do. There is a decent chance the pipes in between all/some of those joints never seated properly and are sucking some air. The pipe into the pump on the suction side is also noticeably crooked.....another "no no".

    If you are intent on stopping your suctions side leaks, I would redo that entire side by cutting it loose at the pump and cutting all the pipes at ground level and installing all new correctly.

    If you are not familiar with PVC, a good service tech should be able to do that in a few hours + 2 new Jandy valves.

    I would also install a union or 1/2 union in front of the pump so you can simply unscrew the pump if it needs repair/replace in the future
    The pool wasn't losing its prime last year. I'm 99.9% confident that the air is not being pulled in by the jandy valve area. The run from the last jandy into the pump is reasonably straight (keep in mind the barrel distortion with cell phone camera lens). Plus, I know it's not leaking after the last jandy because when I set up the pump to pull from teh spa only I have no air entering the system.

    I did a lot of listening, pouring water over the connections around the jandys as well. The pump/line loses it's prime very quickly, I'm pretty sure I would be able to spot it above ground.

    I live in Houston, so there is no bedrock, everything just settles/moves around on the soupy soil. I had the leak detection guys out and fixed a couple returns next to the pool earlier this year (March) - one that had been severed due to soil movement. My gut feeling is the above ground pipework is ok.

    The picture is a week old. I installed a couple union valves over the weekend (one before the pump and one after).

    I really appreciate your thoughts, I think I'm at the point where I get the leak detection guys out again.

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    Re: pump losing prime - did I miss anything obvious

    I should add one more thing that will make you laugh.

    The PVC pipes that are screwed into the multi-port appear to be glued. I tried really hard to unscrew them on Sunday and I'm pretty sure if I put any more force on the channel locks some of the PVC would crack.

    That discovery really ticked me off...

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    Mod Squad Bama Rambler's Avatar
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    Re: pump losing prime - did I miss anything obvious

    First a little terminology lesson, so I don't get confused.
    To us when you say return, it means the water returning to the pool/spa from the filter. Water from the pool/spa to the pump, is the suction side.

    Have you tried setting the valves to where you get the most air and running water over the pump basket and fittings to see if it lessens the air getting in. Logic would suggest that the leak is in the main drain line or valve, BUT since the spa is raised it would have less suction head and if the leak is at the pump suction port for instance it would leak less when drawing from the spa than it would the pool and since the main drains would have the most suction head it would leak in more air than the other suctions.

    Does the pump basket get air in it with the pump off?
    Does it make a difference how the valves are positioned?
    Dave J. TFP Moderator
    24' x 52" Round AGP. 2hp/¼hp SPL Power-Flo 2-speed pump. 200sqft Waterway Cartridge Filter. 45MHP2(3GPD) Stenner Peristaltic Pump
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    Re: pump losing prime - did I miss anything obvious

    Quote Originally Posted by Bama Rambler
    First a little terminology lesson, so I don't get confused.
    To us when you say return, it means the water returning to the pool/spa from the filter. Water from the pool/spa to the pump, is the suction side.
    Yeah, sorry about that. I probably shouldn't have added that last comment, but indeed a couple pressure side leaks (returns) were repaired on the lines going back to the pool. They did not find any suction side leaks at the time (back in March).

    Quote Originally Posted by Bama Rambler
    Have you tried setting the valves to where you get the most air and running water over the pump basket and fittings to see if it lessens the air getting in. Logic would suggest that the leak is in the main drain line or valve, BUT since the spa is raised it would have less suction head and if the leak is at the pump suction port for instance it would leak less when drawing from the spa than it would the pool and since the main drains would have the most suction head it would leak in more air than the other suctions.
    So the jandy on the left lets me choose between spa and pool. When it's on spa only, I get no air while the pump is on. Also, no air enters the system while the pump is off. When that Jandy on the left is on pool only I get quite a bit of air while the pump is on, also when the pump is off air rapidly enters the system. I figure it takes about 30 minutes for enough air to get into the system to where I have to put water in the pump and prime it. So the jandy on the right controls whether water is pumped from the bottom of the pool or the skimmers. When I'm on bottom of pool only and the pump is running, I get quite a bit of air. When I'm on skimmer only, I get quite a bit of air, but not as much as bottom only.

    I agree, the spa is raised, so there will be less suction. However, the above indicates to me that the air is likely being sucked in between the pool and the jandy valve on the left (no air is pulled in while the spa only is running).

    Quote Originally Posted by Bama Rambler
    Does the pump basket get air in it with the pump off?
    Yes, very quickly. If I leave the jandy lines up to spa only, no air enters the basket.

    Quote Originally Posted by Bama Rambler
    Does it make a difference how the valves are positioned?

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    Mod Squad Bama Rambler's Avatar
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    Re: pump losing prime - did I miss anything obvious

    Good clarification. I wasn't sure if air was getting into the system when the pump was off in some positions.

    That leads me to believe that the leak is probably in the piping between the two valves, or the second valve is leaking (possibly around the stem).
    Dave J. TFP Moderator
    24' x 52" Round AGP. 2hp/¼hp SPL Power-Flo 2-speed pump. 200sqft Waterway Cartridge Filter. 45MHP2(3GPD) Stenner Peristaltic Pump
    Pool School ----- Pool Math ----- TF-Test Kit

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    Re: pump losing prime - did I miss anything obvious

    Quote Originally Posted by Bama Rambler
    Good clarification. I wasn't sure if air was getting into the system when the pump was off in some positions.

    That leads me to believe that the leak is probably in the piping between the two valves, or the second valve is leaking (possibly around the stem).
    No worries on the clarification, I'm not the best writer.

    You're probably right about the leak. Is there anything I can do to confirm it short of redoing the pipework?

    Could I just caulk all the joints and see if it slows the air? I imagine a bit of caulk would slow the flow of a suction leak.

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    Mod Squad Bama Rambler's Avatar
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    Re: pump losing prime - did I miss anything obvious

    Did you run water over it with the valves in different positions to see if it made a difference?
    Dave J. TFP Moderator
    24' x 52" Round AGP. 2hp/¼hp SPL Power-Flo 2-speed pump. 200sqft Waterway Cartridge Filter. 45MHP2(3GPD) Stenner Peristaltic Pump
    Pool School ----- Pool Math ----- TF-Test Kit

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    Re: pump losing prime - did I miss anything obvious

    Quote Originally Posted by Bama Rambler
    Did you run water over it with the valves in different positions to see if it made a difference?
    I did try this and it didn't seem to make much difference. I may get my wife to help observe this time.

    BTW - thanks for everyone's advice.

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    Re: pump losing prime - did I miss anything obvious

    Well lesson learned - always trust the pros at TFP.

    I spent about 20 minutes soaking various parts of the suction side pipes and valves. Just as I was about to give up I decided to soak over the outlet from the pump immediately after turning off the pump and well, the air filling slowed dramatically (see picture).

    It turns out the suction side leak is where the junk catcher basket thing is bolted to the pump. I guess the amount of air coming in when I adjusted jandy valves had more to do with how much suction force was put on the leak.

    So I jiggled the pump a bit and the basket stopped filling with air. When I turn on the pump almost no air is coming into the system. I put some silicone goop on the connection for now, but will do a proper repair on the weekend.

    Success.

    So, what I totally neglected to mention was, that I had the local pool guys replace the 30 year old rusted out gas heater with a new one. The slow priming issue started after they did this. They must have knocked the pump a bit doing the install and maybe I knocked it more later.


    Now a question for the mods - is it possible for me to contribute $70 to bump my pledge level from lifetime to platinum? Or do I need to contribute the full $100?
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    Mod Squad jblizzle's Avatar
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    Re: pump losing prime - did I miss anything obvious

    I am pretty sure you can just donate the difference to "upgrade". Glad you got it figured out and are willing to help maintain the site, thanks!
    Jason, TFP Moderator
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