PEX A union fitting

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Vdawg

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I am going to be moving into a new house with PEX A throughout. It will have a water softener loop in the garage. When I install the water softener, I'd like to add an additional ball valve as a main shutoff (I'll use this later with automated leak detectors to shut of the water in the event of a leak) as well as a tee with a pressure gauge and a bypass for the softener. I may even add a whole house filter later.

So, when I cut the loop to add in my components, I was thinking I'd like to make my assembly (shutoff, gauge, bypass, etc.) be removable so I could reconfigure/redo it at a later date if needed, or even just to service the various components. Since the water softener loop only extends from the wall about 6 inches, I wouldn't want to have to cut the pipe back more than once. So my thought was to cut the loop as far out as possible and add in a union of sorts on the incoming and outgoing sides so that anything I attach in between could be disassembled and added back without needing to cut the original incoming/outgoing loop pipes back to the wall.

With regard to PEX A, the closest thing I could find to a union was a female swivel adapter (FIP), which I assume would mate to a male adapter (MIP). Is this a reasonable solution or is there a better type of PEX A fitting that allows disassembly and reassembly? I also thought I could use Sharkbites since they are removeable (and all of this work would be exposed at all times), but they could leave the outside of the PEX scored so that they couldn't be put back on without cutting back the original PEX again to get a pristine seal for the o-ring. Thus, my desire for some type of standard union type fitting. A union would also allow me to build my "assembly" separately from the loop rather than having to build it "in place" (not that it's a big deal but just a bit easier).

Thanks!
 

John Gayewski

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John Gayewski

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If you don't want to sweat the one end they have them threaded on both ends also.
 

Gsmith22

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I was looking to add union fittings to my water treatment too with a pex based plumbing system and all I could find were unions fittings in brass, stainless, or cpvc (also pvc but shouldn't be used in water supply inside house). Using threaded FIP to MIP pex fittings isn't a union because you can't spin the connection apart once the pex is connected to both sides. I never could find anything pex based so I think what was suggested above is what you have to do - transition pex to something else and then back to pex if you want a union. I would avoid cpvc.
 

Vdawg

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I was looking to add union fittings to my water treatment too with a pex based plumbing system and all I could find were unions fittings in brass, stainless, or cpvc (also pvc but shouldn't be used in water supply inside house). Using threaded FIP to MIP pex fittings isn't a union because you can't spin the connection apart once the pex is connected to both sides. I never could find anything pex based so I think what was suggested above is what you have to do - transition pex to something else and then back to pex if you want a union. I would avoid cpvc.
Yeah -- sounds like the solution is to terminate the pex with a brass MIP adapter which would be threaded into a brass union (perhaps like the union ball valve mentioned earlier), then out of the other half of the union with another MIP to Pex adapter to get back to pex. Or, use the pex female swivel adapter directly to a pex male threaded adapter if that's essentially the same as a union.

I guess the transition technically could be pex to brass MIP adapter which is then threaded into a FIP adapter directly. Yes, you would then have to cut the pex above the threaded adapters to unscrew them. But if the assumption is that I would be removing the "assembly" in order to add/remove/change/fix components, then the assembly would be recreated, then the two threaded (F/M) adapters could be reassembled first, THEN the new assembly attached to the already-connected threaded adapters. The result would still be the preservation of the original portion of the soft water loop which is the original priority.

Overall, though, I still prefer the idea of a true union just in case I don't reassemble the two adapters tight enough on the first try, then add the new assembly and the adapters leak a little, there's no way to make them tighter once the pex is attached. With the union, I'd have some chance of tightening it. The female "swivel adapter" I mentioned earlier actually has a rubber gasket in it, so I imagine it's different than a typical union in that way? I don't know which one is more/less likely to leak... I've never used a standard union before, but I did install about a dozen CPVC angle stops in this house (replacing old multi-turns), and they seem to work on a similar principal as the female swivel adapter I was looking at. These worked well and were easy to install. Since the originals were the same CPVC connection, I left that part on the stubout replaced the rubber gasket and valve body with the new one and it threaded right on to the old "nut" portion, leak free!

screencapture_000753.png
 

Vdawg

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You can get a F1960 - ball valve - union - FIP assembly, e.g. http://www.webstonevalves.com/default.aspx?page=item+detail&itemcode=H-30423W&catlist=571&parent=203 (for 3/4", also available in 1/2" and 1" at least)

That will let you shutoff the PEX connection and disconnect the union, so that you can work on the union side without draining everything.

Cheers, Wayne
Good point. Being able to shut off the water right at the union is a nice benefit of that assembly.
 
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