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Thread: Bad brass threads?

  1. #1
    DIY Member M3's Avatar
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    Default Bad brass threads?

    I'm putting in a moen exact temp shower/spa with 3 controllers; so I have a brass cross between the mixing valve and the controllers... Unfortunately I have had a slow leak twice now in the same threaded end of the brass cross.

    The first time, admittedly the nipple wasn't tight enough, but upon pulling it all out again I cleaned it all up and put in plenty of Harvey'sTFE compound...and made it good and TIGHT! Out of 14 different threaded joints on this assembly, only this one joint is leaking - twice!

    I checked it every day and thought I got it licked, but now after 5 days water is seeping through!! I'm wondering if the threads can have a defect...? Should I purchase a new cross and nipples when I take this apart again...? If I put in a new cross I'll have to take apart even more of the assembly...Any other suggestions? What a pain.

  2. #2
    Plumber krow's Avatar
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    Try T-tape and thread dope together on the same joint, and be generous with it

  3. #3
    Moderator & Master Plumber hj's Avatar
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    Use solder fittings and adapters to eliminate the threaded connections. Does the shower valve have male or female connections?

  4. #4
    DIY Member M3's Avatar
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    Quote Originally Posted by hj View Post
    Use solder fittings and adapters to eliminate the threaded connections. Does the shower valve have male or female connections?
    The shower valve is all female threaded and Moen suggested not to solder... I don't know if it would void any warranty or not.

  5. #5
    Retired Defense Industry Engineer jadnashua's Avatar
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    Many of the valves are sized so you can either use a threaded connector OR use the female body of the valve as a coupling and slide the pipe inside and solder. The only thing with soldering it is, if you don't remove the cartridge while soldering, you can ruin it. Moen probably doesn't want people requesting a new cartridge because it leaks after not being removed while soldering, verses threading the pipe on. Because the valve body acts like a big heat sink, it is a little harder to get it hot enough to do a good solder joint than a simple copper joint.

    Some of the brass threaded fittings are junk...to save a bit, they don't change the cutter or keep it sharp, and the threads are rough and sometimes torn. It's really hard to get a good seal. the belt and suspenders of tape and dope can help.
    Last edited by jadnashua; 02-19-2010 at 07:30 PM.
    Jim DeBruycker
    Important note - I'm not a pro
    Retired Defense Industry Engineer; Schluter 2.5-day Workshop Completed 2013, 2014

  6. #6
    Moderator & Master Plumber hj's Avatar
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    They meant not to solder to the valve body, but unless the connections were male threads, the copper would not solder directly to it anyway. You cannot do it with female connections on the valve, but all you have to do is solder the tubing to an adapter and then tighten the adapter into the valve.

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