View Full Version : Testing soldered sweat/PEX adaptor joint?

01-08-2006, 09:01 PM

I was 'referred' here from reading John Bridge's forum, and I have learned a lot just browsing. I am plumbing my new master bathroom, and have a few questions that have not yet been answered through reading.

I have succesfully soldered many copper/copper pipes, fittings etc, but the shower valve is giving me the willies. I am using a PEX Manabloc manifold system. The American Standard single tub/shower valve has 1/2" sweat connections, and I'm trying to solder male sweat/PEX adaptors into three of the ports.

I've disassembled the valve, so I have just a big, heavy chunk of brass on my workbench. I'm using propane, and yes, it takes a long while to heat up. The joints are pretty loose (when dry fitting), and it seems to be taking a bunch of solder. One joint I already know is bad (it wiggled when I test fit the PEX to it!). Any hints on flux, solder, heat application for this type of connection? My problem may be that the flux is long gone by the time it is hot enough.

Is there a way to test the joints before crimping them all up and putting water pressure to it? If I do crimp the PEX to the adaptor and then find that the soldered joint leaks, how do I take the crimped connection apart? I had thought about 'Dremeling' somehow the crimp ring and then sliding the PEX off. Is the adaptor damaged by the crimping, and do I need to get a new one? It would be difficult to cut the PEX back, an inch at a time, until I got a solid joint.

Thanks for any input,

01-09-2006, 02:20 AM
The fittings shouldn't be that loose . Are you sure they are 1/2" and not 3/8"?

How about a piece of 1/2" copper sweated into each port then a pex connector at the end of the copper. Give you something more solid to secure to the studs....


01-09-2006, 04:04 AM
Here is what I would do. Take the male PEX out of the valve. Solder in copper lines with maybe a 90 and a stub of copper heading towards the direction of the PEX and solder on a female copper X PEX adapter. This will make soldering the valve easier and you can anchor the valve well with the copper. Use copper up to the shower arm and down to the tub spout. You can not solder the fitting with the PEX attatched.

01-09-2006, 04:27 AM
The joints are pretty loose (when dry fitting), and it seems to be taking a bunch of solder.

Thanks for any input,

You may have a bigger problem. If you are doing this on a work bench and it seems to be "taking a bunch of solder", you may have heated it up too much and due to the loose joint, and if it was at the right angle, you may have allowed soder to run into the inside of the valve to the pressure balancing portion of the valve. It takes very little solder to do the job. About 1/2 -3/4" of solder wire is all you need if done right. The joint shouldn't be loose like you are describing. I can't tell if it is the valve or the fitting. What brand of valve is it?

01-09-2006, 04:53 AM
Wow, those were fast replies; I thank you. Definately 1/2" ports on this single handle American Standard valve. I, too, had thought of coming out of the valve with short pieces of copper, and then putting a female adaptor on that to connect to the PEX. In fact, that is sorta what I did on the "tub" port, which I capped off.

I don't think that I have a problem with solder running into the valve. At least I didn't see any, and I "blew" into the ports after reassembling the valve while operating the handle, and it seemed to work OK.

I guess the big questions that I have remain, and that is how to test this for leaks before crimping the pex on. If there isn't a good way to do that, then how best to take it all apart if there are leaks?

Thank you for the advice,

01-09-2006, 04:59 AM
Unsolder it and wipe it out of the port as best you can with a clean rag then use a fitting brush. B4 you resolder pick up and use a pretinning flux. Blowing into the valve won't tell you anything other than air goes from point A to point B.

01-09-2006, 05:06 AM
If the fitting is not "snug" in the valve, you will never make a good solder joint to it. PERIOD! So your real problem is to discover why the fittings seem to be loose in the valve.

01-09-2006, 09:37 PM
Here's an update after some work tonight. I couldn't find Oatey 95 flux in my little town today. But I got some some Nokorode paste, much better flux than what I was using, and some Sterling solder to boot.

Cleaning the inside of the valve ports was a nasty job, and I couldn't get them 100% clean of solder. But I got them as smooth and clean as possible.

The 1/2" copper pipe fit very snugly, which the male adaptors previously did not, for some reason. They were 1/2", after all, but were very loose. That may have been the biggest difference right there. The better flux and solder didn't hurt either, I'm sure.

That seemed to work very nicely, and I'm much more confident about these joints. :) Still, though, my original main question(s) remain(s):

Is there any way to test this without crimping the PEX on? If it fails, what must I do then? Would I have to cut all three crimp connections out, re-solder, and then crimp again, possibly using a (PEX) coupling since my slack is now gone? :confused:

01-10-2006, 04:15 AM
Sounds like you stubed out with copper. How long is the copper B4 you get to the PEX adapter.

01-10-2006, 08:34 PM
Hello, and thanks, Cass. I had to to my veterinary thing all day today, and just got home @ 11PM. Tomorrow is my plumbing day.

I had considered your good advice from the other day about going out of the valve, turning 90 degrees down, and then fitting a pex adaptor on. I can still do that with my second shower valve for this shower (his & hers). Due to the stiffness of the 1/2" pex and turning radii and kinking and all that, I had decided bring it up in the adjacent stud bays and go into the valve horizontally, drilling a 3/4" hole in the studs. I have the holes drilled and PEX run already at my building site (new home, 12 miles away), and am soldering the valve at my current house. So, after all that, I have only about a 2" piece of pipe coming out of the shower valve, and the female PEX adaptor straight out from that.

It might work better to go with your idea for my wife's side, so I can get further away from the valve before the PEX is attached. Of course, if all my joints are good, it's a moot point! :)

Never having worked with PEX and crimp connections before, I don't know how they are taken apart. I would guess that the crimp ring needs to be cut. Side cutters might not be heavy enough, or I might not be strong enough. A Dremel? Then cut a small piece of the PEX off and re-attach after soldering again... That's what is in my head now. I can't think of a way to test the solder joints before installing everything.

Thanks, again. You folks have been wonderful.

01-11-2006, 04:17 AM
They make a special tool for that. Right now I use a saws all and cut, just the band, at an angle. Then cut the pipe square again.