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Thread: quick connect/disconnect unions for a dynamo?

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    quick connect/disconnect unions for a dynamo?

    I have a Pentair Dynamo pump that I believe has a shaft seal leak based on what I've read. I am confident that I can fix this on my own, but I'm going to have to cut the PVC going into the pump so I can remove it and do the seal replacement. It is plumbed right now directly into the pump without any kind of quick disconnect union that can be screwed off. When I re-plumb this thing I'd like to correct this plumbing mistake and use unions(or whatever it is that I need) to allow for a quick removal of the pump in the future without having to cut PVC and replace it. My plumbing is 1 1/2 PVC and I'm wondering if someone can point me to exactly what I need as far as a union or such to reconnect this the proper way this time around? I can snap a photo if needed to show what I've got here
    24' AGP vinyl, 3/4hp Pentair 2-speed, Pentair Quad DE 60
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    Patrick_B's Avatar
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    Re: quick connect/disconnect unions for a dynamo?

    Generally, it's not a good idea to install unions on the suction side of your pump. It creates potential for suction side air leaks. You really don't want any of those. It's does make removal a real pain, but suction leaks are worse to have an issue with.
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    Mod Squad jblizzle's Avatar
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    Re: quick connect/disconnect unions for a dynamo?

    So I assume you can not just take the motor off because it is too close to the house or something? You should not need to do any plumbing work to change the shaft seal ... unless the installers were their typical selves by making the trivial impossible
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    Re: quick connect/disconnect unions for a dynamo?

    Thought I'd throw out there that a properly aligned and tightened union should rarely be a problem. The ability to remove a pump and motor together and work on them in a clean environment, preferably at workbench level is much more of a positive than the low risk of a suction side leak. Minimizing the stresses caused by misaligned rebuilt pipe sections and subsequent failed glue joints is also a concern.

    I've seen recommendations on this site that CPVC fittings should be used to attach to the pump, just because that material has a higher temperature rating and will endure better if the pump conducts heat to the piping due to a dry run episode. There's a company named Praeher that manufactures many versions of unions and fittings meant for pump connections. Pentair also probably sells unions they specify for your pump.
    21K gal 16' x 40' in-ground pool built 1959, old school with Jacuzzi bronze pump, American Products 24" Sand Filter & Americana Multiport valve, Jandy Lite2 millivolt heater, Coverstar cover, and classic Kreepy Krauly.

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    Re: quick connect/disconnect unions for a dynamo?

    Quote Originally Posted by gtemkin View Post
    Thought I'd throw out there that a properly aligned and tightened union should rarely be a problem. The ability to remove a pump and motor together and work on them in a clean environment, preferably at workbench level is much more of a positive than the low risk of a suction side leak.
    I agree 100%

    My home setup came with 4 inch long rubber hoses connecting the suction and pressure pump sides.

    Both were bulging badly when I bought the house and the previous owner told me there was no other
    way to make the pump removable and that I should tighten the hose clamps every season. LOL.

    After taking posesion I promptly had a good rated local pool shop come and remove the rubber unions.
    and replace them with PVC and threaded unions. The alignment is perfect and aside from me
    accidentally opening the main drain valve too fast and water hammering the pump basket, (which I fixed with a dab of rtv to the union threads)
    It has held perfect prime for weeks on end.
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    Re: quick connect/disconnect unions for a dynamo?

    Quote Originally Posted by jblizzle View Post
    So I assume you can not just take the motor off because it is too close to the house or something? You should not need to do any plumbing work to change the shaft seal ... unless the installers were their typical selves by making the trivial impossible
    I don't believe I can replace the shaft seal without removing the whole pump assembly and not just the motor. At least not based on what I've seen online, and by looking at my pump and its leak. I guess I'll check with Pentair about the proper unions for the Dynamo. I wouldn't think it would be too complicated(hopefully). Was just hoping someone already knew exactly what to use with the dynamo and 1 1/2 pipe. Thanks guys for the comments.
    24' AGP vinyl, 3/4hp Pentair 2-speed, Pentair Quad DE 60
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    Re: quick connect/disconnect unions for a dynamo?

    My preference is schedule 80 pvc unions... A little more expensive than sched 40 but they're less likely to crack.

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    Re: quick connect/disconnect unions for a dynamo?

    I put unions on both sides of my pump......so far, so good after about 9 years. Of course, if I get 10 years use out of the pump and then have to replace, I'm not sure the unions were that important. It'll surely make it nice when that replacement time comes, however
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    Re: quick connect/disconnect unions for a dynamo?

    http://www.aqua-man.com/schematic.asp?kc=S877&s=full
    even though this isn't a dymano, its still a Pentair with 1 1/2 threaded suction and pressure openings. Is this probably what I'd need(parts 1, 2,and 3) and would allow simple 1 1/2 pvc to connect? Sorry if I'm sounding like a plumbing idiot and this is a dumb question. OR would I just need the union nut and O-ring and not part # 2(the adapter)?
    24' AGP vinyl, 3/4hp Pentair 2-speed, Pentair Quad DE 60
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    Re: quick connect/disconnect unions for a dynamo?

    Quote Originally Posted by jblizzle View Post
    So I assume you can not just take the motor off because it is too close to the house or something? You should not need to do any plumbing work to change the shaft seal ... unless the installers were their typical selves by making the trivial impossible
    Ok I clearly didn't know what I was talking about earlier, and you were right. I WAS able to remove the motor assembly and get to the shaft seal without taking the plumbing loose. I've never changed a shaft seal in a pump before, so this was a nice learning experience for me and a cheap repair! I'd still like to re-plumb with quick connect unions at some point in the future, but for now all is well.
    24' AGP vinyl, 3/4hp Pentair 2-speed, Pentair Quad DE 60
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    Mod Squad jblizzle's Avatar
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    Re: quick connect/disconnect unions for a dynamo?

    Good to hear
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    Re: quick connect/disconnect unions for a dynamo?

    A lot of schedule 80 unions are the exact same as their schedule 40 counterpart. I guess the manufacturer though being able to use the same mold would be cheaper than the resin costs.

    I like quality unions. The ones that HD and lowes sell are decent. Spears has always been my favorite.
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    Re: quick connect/disconnect unions for a dynamo?

    I like the hydro unions the 1.5 and 2 inch inner change comes in handy

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