Shower Mixing Valve Replacement Advice

Discussion in 'Shower & bathtub Forum & Blog' started by lkstaack, May 21, 2012.

  1. lkstaack

    lkstaack New Member

    Messages:
    19
    Location:
    San Diego, CA
    I would like to replace an old Delta mixing valve with a newer one. Does it look like I have enough room from the front without having to cut drywall in the back? I couldn't find a YouTube video that showed a mixer replacement from the front. In my mind, I think that I could sweat the slip joints on one end while unscrewing them on the other. Will that work? If so, could I do the same when installing new joints? Or should I just cut them?

    Will I need to tape the threads? If so, will re-soldering the joints melt the tape? What is the correct procedure?

    I have a little experience soldering copper pipe, but not alot and no experience soldering inside a wall. Any advice from experience would be appreciated...or perhaps you can direct me to a good DIY site or video. Thank you.

    Attached Files:

  2. johnjh2o1

    johnjh2o1 Plumbing Contractor for 49 years

    Messages:
    1,142
    Location:
    South*East
    It can be done but there is a risk of fire. There is a product that can be sprayed inside the wall on the wood framing that helps. But if you have little experience using a torch I wouldn't advise you to try it. It's far easier to replace it from the back side. Cutting and repairing drywall is not that hard to do.

    [​IMG]
    Laco flux

    John
    Last edited by a moderator: Feb 5, 2014
  3. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
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    Location:
    Cave Creek, Arizona
    The valve YOU will purchase will probably have screwed connections like that one, so it will be almost impossible to replace it through the opening. A plumber would use one with solder connections which gives some latitude for the piping.
  4. lkstaack

    lkstaack New Member

    Messages:
    19
    Location:
    San Diego, CA
    You are right, the Delta set I purchased from HD is threaded. Why in the world do these valves have threads? One with solder connections would be much better.
  5. lkstaack

    lkstaack New Member

    Messages:
    19
    Location:
    San Diego, CA
    I thought that might be the case. I don't mind opening and repairing drywall...it's getting to that drywall that is problematic. I'll have to reconsider my plan.
  6. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    21,824
    Location:
    New England
    On many valves, they can be soldered OR threaded...if yours has male threaded fitting on the outlet, it is likely designed to allow a soldered connection on the inside of the fitting as well so you have a choice.

    If you don't want to cut drywall, and can accept a larger opening in the shower, Delta and most other companies make what is called a rennovation or remodel plate that is deisgned to cover the larger hole. You install that plate, then install the valve's trim on top of it. They typically don't cost that much.
  7. jimbo

    jimbo Plumber

    Messages:
    8,997
    Location:
    San Diego
    Your delta probably has male threads, and the inside of that fitting is machined to copper tube size for optional sweat.

    [​IMG]
    Last edited by a moderator: May 22, 2012
  8. lkstaack

    lkstaack New Member

    Messages:
    19
    Location:
    San Diego, CA
    If I understand correctly, 1/2" copper pipe can be soldered into the threaded fitting of the valve? I can use the threaded valve without using threaded connectors? That would make things alot simpler. The fitting looks like it would accept pipe.
  9. jimbo

    jimbo Plumber

    Messages:
    8,997
    Location:
    San Diego
    yes..............
  10. lkstaack

    lkstaack New Member

    Messages:
    19
    Location:
    San Diego, CA
    Thanks! And thank you for your patience. However, there is another issue that prevents me from starting this job. I'm hoping that there is a procedure that will allow me to complete this job from the front.

    I'm thinking that I need to cut off the old valve as close to the old fittings as possible and solder four pipes in the new valve so that they are just a little shorter than the pipes (hot, cold, shower, tub) that they will be soldered to. Slip couplings will have to be slid down the pipes so that the new valve can be inserted where the old one was, and then slid back onto the joint for soldering. If the slip couplings are not slid back past the pipe edge, they will interfere with the tight clearances between valve and the four pipes for insertion.

    However, it doesn't look like there is enough room for the slip couplings to be slid back for insertion. I only have 1/2" of copper pipe between the old valve and a 90* elbow for both hot and cold water (you can see it in the pic above). I'll have about 1/2" of pipe extending out from the new valve. The slip coupling is about 1" long. So, anywhere I put the coupling, it will extend 1/2" past the pipe edge, preventing insertion of the valve.

    The only solution I can think of is to open up the back of the wall to gain access to the 90* elbows, remove them, and then replace them when inserting the valve. Is there another option?
  11. jimbo

    jimbo Plumber

    Messages:
    8,997
    Location:
    San Diego
    Replacing a shower valve from the shower side is a challenging task. You have mentioned some of the issues....need a lot of "fiddling" with fittings, etc. Then there is the fire issue, as mentioned by others.

    If there is ANY way you can open up the back wall, JUST DO IT!!!!!!
  12. lkstaack

    lkstaack New Member

    Messages:
    19
    Location:
    San Diego, CA
    OK, I will.
  13. Terry

    Terry Administrator Staff Member

    Messages:
    14,799
    Location:
    Bothell, Washington
    The first time I heard about replacing a shower valve was when my friends dad, an engineer from Boeing related the $5,000 fire in his home from soldering in the wall to replace a shower valve. That was in the 60's
    With inflation I can see it being a lot more. We sometimes pick up those plastic pop in panels for covering the hole in the drywall.
    http://www.fluidmaster.com/our-products/access-panels/14-x-14-access-panel.html
  14. lkstaack

    lkstaack New Member

    Messages:
    19
    Location:
    San Diego, CA
    Thanks, Terry. I'll be sure to keep obvious flammables away from the torch, keep a barrier between the drywall and torch (tin foil?), and have a fire extinguisher next to me. That panel looks great, but I'm going to have to use something solid since the wall is a garage fire wall.
  15. lkstaack

    lkstaack New Member

    Messages:
    19
    Location:
    San Diego, CA
    Sodering Advice

    Well, I've taken everyone's advice and opened the wall behind the mixer valve. The piping is a little more complex than I anticipated, so I request advice how to proceed.

    My tentative plan is illustrated on the attached pic; please let me know if it .

    1. Cut the copper pipe near the red lines.
    2. Solder new pipe between the hot water line and the valve.
    3. Solder new valve onto the new hot water pipe.
    4. Solder slip joints between new valve and shower/tub pipes.
    5. Solder new cold water Tee onto valve.
    6. Replace and solder new cold water connection.

    I'm not certain I understand why the original plumber reduced the 3/4" cold water line to 1/2"; was it to fit that tight 180*. Couldn't you but two 3/4" Tees together?

    Anyway, this soldering job is more complex than anything I have done before. I'll call a professional if I have to, but you never learn anything if you don't try it yourself. What do you think?

    Attached Files:

  16. Terry

    Terry Administrator Staff Member

    Messages:
    14,799
    Location:
    Bothell, Washington
    I can't look up the wall, but it looks like 3/4" air chambers to me. I bet they have caps on them and they are about 16" long.

    I would cut near the valve, and use couplings on the 1/2" pipe to the valve. It looks like you have some room to push the pipes apart there. You're almost done now.
  17. lkstaack

    lkstaack New Member

    Messages:
    19
    Location:
    San Diego, CA
    Thanks, Terry. If I understand you correctly, the job will be alot easier than I thought.

    You are saying that I only need to cut the 1/2" pipe at the old valve and use couplings? I will be able to slide the couplings up the shower/tub pipes, so that is not an issue. However, you think that I will be able to bend the 3/4" pipes far enough to fit in the couplings in areas marked A and B on the attached pic? I'll only have about 1/2" of copper pipe coming off the 3/4" pipe after cutting off the old valve and another 1/2" coming from the new valve. Is that enough material to get a good solder connection?

    Attached Files:

  18. Terry

    Terry Administrator Staff Member

    Messages:
    14,799
    Location:
    Bothell, Washington
    I think you will find that when the pipe is cut, that you will be able to move the copper pipes enough to work on that. You may need some short pieces of pipe to make up the difference. You will want to remove the water in the line, maybe a vacuum will do that.
  19. lkstaack

    lkstaack New Member

    Messages:
    19
    Location:
    San Diego, CA
    Thanks. Won't the water drain out of the cut pipes and open faucets inside the house?
  20. Terry

    Terry Administrator Staff Member

    Messages:
    14,799
    Location:
    Bothell, Washington
    It looks like the pipe dips down below the valve.
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