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Thread: Need "best method" for LEAK-FREE threaded fitting connection

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    Need "best method" for LEAK-FREE threaded fitting connection

    Well Ė today I upgraded my old, standard pump to a Pentair IntelliFlo pump Ė for all the obvious reasons.
    I was quite disappointed to find out after the installation, I have a major leak where the threaded insert fitting screws into the outlet on the pump.
    Though Iím bummed about the rework, Iím more annoyed / concerned because I donít know where / how I went wrong.

    The plumbing procedure I employed was this:
    (1) I applied a liberal amount of Rectorseal thread sealant on the male PVC fitting AND the female pump outlet threads.
    (2) I hand tightened the PVC fitting until I could not turn it anymore
    (3) Using a strap wrench, I finalized the fit by turning the threaded fitting an additional 360 degrees (one revolution).
    (4) I completed plumbing the rest of the circuit with standard PVC primer & glue method (no leaks on any of these connections)

    Does anyone have a method that they know works for sure?
    I need to know how to do this right so that I donít waste more time, effort & money on round 3.

    All advise is greatly appreciated!!
    Thanks, ScooterBeat

  2. Back To Top    #2
    Mod Squad jblizzle's Avatar
    Join Date
    May 2010
    Tucson, AZ

    Re: Need "best method" for LEAK-FREE threaded fitting connec

    Sounds like the way I would do it. Add a union in the straight section of pipe into/out of the pump so that the rework is easy if it leaks again.
    Jason, TFP Moderator
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  3. Back To Top    #3
    asxetos's Avatar
    Join Date
    Jul 2012
    Athens, Greece

    Re: Need "best method" for LEAK-FREE threaded fitting connec

    Undo the fitting, clean threads as best you can, then use Teflon tape (lots of it).

    Hand tighten only, then test run pump to test for leak.

    In case of leak, tighten more only to stop the leak and no more than that.

    Remember, LOTS of Teflon tape, much more than you think you might need to get a seal, so much Teflon that it would be hard to screw the fitting after only one turn by hand. If it screws easily you have too little tape in there.
    Donīt be fooled by the sheep on my bike, I swim with fish in my sound equipped pool.

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    In the Industry

    Join Date
    Jul 2012
    Saugerties, NY

    Re: Need "best method" for LEAK-FREE threaded fitting connec

    I agree with asxetos about teflon tape. I would probably go a little bit tighter than he says, but if you aren't really experienced and haven't developed a feel for it, you can easily crack the pump housing if you over tighten. So its probably a good idea to start with hand tight and work your way up.

    jbizzle's suggestion about adding a union is a great idea. This will let you start at hand tight, and add a quarter turn at a time until it doesn't leak anymore without having to keep cutting the pipe over and over again.

    Pool Technician
    Saugerties, NY

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    Join Date
    May 2013

    Re: Need "best method" for LEAK-FREE threaded fitting connec

    I saw these on the shelf on my local pool/spa shop and just had to have 2. I used one at each end of the pump. Glues right up to my 1.5" pvc. Notice the o-ring where it seals against the pump. I guess these are primarily used for spa pumps being they call them hi-temp unions. I wanted a union there anyway so I figured I might as well get one that provides a good seal at the pump.

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  6. Back To Top    #6
    JasonLion's Avatar
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    May 2007
    Silver Spring, MD

    Re: Need "best method" for LEAK-FREE threaded fitting connec

    For pipes over 1" I prefer to use a non-hardening thread sealant compound rather than teflon tape, hand tight plus half a turn. As always, check and clean the threads beforehand as needed.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
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  7. Back To Top    #7

    Re: Need "best method" for LEAK-FREE threaded fitting connec

    So this gets interesting Ė

    The short answer is: I WIN, THE LEAK LOST!

    I went down to the local pool parts supply guy (a bit more of a commercial outlet Ė not geared for the typical pool owner). I explained the situation to the guy behind the counter, and his response was pretty alarming. Basically, he told me that Pentair had a design error with the threading on the inlet / outlet for some very large lots of pumps that they sold (kinda hard to believe, I know). Apparently the threads taper down at too tight of an angle to mate properly with the standard off the shelf fittings. This condition is accurate to what I experiencedÖ it was very difficult to tighten the fitting properly and ended up with A LOT of threads on the fitting exposed (not enough threads to contain sealant for ensure contact surface area).

    The solution I ended up with was the very same part as shown in the photo above, posted by mpnret (NJ) (Thanks!!!).
    This part fit VERY well, and that O-ring sure makes a nice seal to the surface of the outlet. I re-piped the entire leg of the circuit, and now I have unions at both ends, so the pump is more serviceable now!
    Not one single drop of water!

    Once again Ė thanks for all the valuable feedback everyone.

    Many Cheers,

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