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Thread: Need to replace Shower mixing valve with separate cutoff valve for inputs.

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  1. #1

    Default Need to replace Shower mixing valve with separate cutoff valve for inputs.


    I livein a ~20 year old townhouse. My old shower valve leaked behind the wall with no symptoms in the part visible during normal use. Lots of damage to the drywall around it and a 2x6 support for the valve before we discovered it. After taking down the tile and drywall we saw the mixing valve itself was leaking, and that it had shutoff valves for both hot and cold input. I immediately turned off both shutoff valves, only to find that the left side shutoff valve itself leaked. Luckily, it seemed to fix itself after a draining maybe 50ml into an improvised catch-can. I think maybe it was just backward drainage of the water column in the part above the valve (?).

    So now I have to put in a new valve and a couple of these shutoffs, I suppose. I understand most valves these days come with threaded interfaces? So this usually means sweating together an adaptor of some type, then screwing that into the valve properly, then sweating the other end of the adaptor onto an approprately disassembled/cut supply line.

    Is this correct? Except that in my case, I will sweat in these cutoff valves after the adaptors or as part of them. I like them. I will install them facing backwards, though, since if this ever needs to be accessed once the shower is assembled, it'll be from behind.
    Last edited by OfficeLinebacker; 11-26-2006 at 10:46 AM.

  2. #2
    Plumber jimbo's Avatar
    Join Date
    Aug 2004
    San Diego


    You have a tough situation here because of the other pipes.

    Valves sold at home stores tend to have threaded connections, because it is supposedly DIY friendly. All brands are availavle from a good plumbing supply, or special order at the home store, with (a) sweat connections and (b) integral screwdriver stops. These stops are located so the are accessible when the round escutcheon flange is removed. No need open the wall to get to the stops. If you are in a single family home, stops are nice to have , but not essential. If it is a multifamily building, stops are important.
    Delta ( a brand much favored by plumbers ) will come with male threads, but the fittings are machined internally to accept a 1/2" copper sweat.

    I don't see where that existing valve was secured by anything except the pipes. It really should be supported more securely.

    Flame protectors are readily available so you will not have to further "toast" the plastic pipes while sweating the copper.

  3. #3
    Master Plumber master plumber mark's Avatar
    Join Date
    Feb 2005
    indianapolis indiana - land of the free, home of the brave....
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    Talking I like the melted pvc plastic

    Thats really not that big a deal....

    If you just go out and buy yourself a DELTA 1700 faucet
    with the stops already brazed into the valve all you have to
    is sloder it all up.... they come ready to go...

    they are available at any plumbing supply
    house for only about 10 bucks more than the
    normal valve without stops....

    and you certanly have a football field of room to work with

    yes it might be a good idea to flatten a coffe
    can or something to use as a heat sheild....

    although the plastic is only singed a little bit,
    you might as well not make it any worse...

    have fun .....
    Last edited by master plumber mark; 11-26-2006 at 06:47 AM.

  4. #4



    Thanks for the tips. I do like the idea of integral stops, just for safety. This is the second floor of a townhouse so single family as far as vertical dimension (nobody's house but mine will get water leaking in if the thing leaks). If it's available, I'd still like to go for the shutoffs. Good to know they have 'em built-in AND that they're designed to be close enough to access without having to get behind the thing (there is really no way to get to this chase area right now other than the plumbing wall of the shower enclosure itself (which is in an alcove--I was thinking of cutting a hole in the side of the alcove the vanity is in so maybe a smaller plumber (and I could barely do it now at 5'11" 180#) would be able to crawl through). I'm glad you guys noticed the singeing. I thought it was pretty comical. There's some on the wood, too. As far as support, there was a 2x6 much like the one for the shower elbow that had all but rotted away so I took it out. I'll be replacing it. Luckily the studs to each side and the one on the bottom weren't too bad. Also I will post a pic shortly that shows a copper support for the tube that goes up.


    Thanks, would simple aluminum foil work? I know I've seen suggestions for other things from this dielectric sandwiched between foil for old capacitors to a soaked towel. I know air is one of the best insulators ever, so would aluminum foil loosely folded a few times (and maybe a rag soaked with cold water in there somewhere) work OK? Also, should I need anything stronger than a pen torch to heat the solder enough?

    Finally, what grit of sandpaper do I use to roughen up the ends about to be sweated?



  5. #5


    Hi. Here are two more pics. The first shows another view of the valve with just a hint of the copper support bar at the top. The second shows the part above the support bar and the shower elbow at top. I cropped these pics to try to show great detail of the important parts and little else. I'll find another version that shows more of the "big picture."

    Note: the picture will likely indeed be big.

  6. #6


    My apologies for the crookedness. The alcove is only 42" deep and my camera doesn't have the widest zoom so I wasn't looking in the viewfinder. Also, not sure what you guys' screen resolutions are like but since the first pic is wider I put the two in the previous post next to each other. Anyway here is a view that shows the one support. There was also a 2x6, which I will replace, below the valve. I can't remember exactly where it was but I'll be able to tell by the nail holes.

    Thanks to all for their comments!

    Last edited by Terry; 09-05-2009 at 05:24 PM.


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