Shower Mixing Valve Replacement Advice

**lkstaack** · 05-21-2012, 08:36 PM

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.

**johnjh2o1** · 05-22-2012, 04:38 AM

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.
http://www.laco.com/productDetail15.aspx

John

hj · 05-22-2012, 07:16 AM

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.

**lkstaack** · 05-22-2012, 07:43 AM

Originally Posted by hj

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.

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.

**lkstaack** · 05-22-2012, 07:44 AM

Originally Posted by johnjh2o1

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.
http://www.laco.com/productDetail15.aspx
John

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.

**jadnashua** · 05-22-2012, 10:29 AM

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.

**jimbo** · 05-22-2012, 11:28 AM

Originally Posted by lkstaack

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.

Your delta probably has male threads, and the inside of that fitting is machined to copper tube size for optional sweat.

**lkstaack** · 05-22-2012, 11:48 AM

Originally Posted by jadnashua

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.

Originally Posted by jimbo

Your delta probably has male threads, and the inside of that fitting is machined to copper tube size for optional sweat.

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.

**jimbo** · 05-22-2012, 06:58 PM

yes..............

**lkstaack** · 05-22-2012, 08:50 PM

Originally Posted by jimbo

yes..............

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?

**jimbo** · 05-23-2012, 06:08 AM

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!!!!!!

**lkstaack** · 05-23-2012, 07:53 AM

Originally Posted by jimbo

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!!!!!!

OK, I will.

**Terry** · 05-23-2012, 09:35 AM

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-produ...ess-panel.html

**lkstaack** · 05-23-2012, 02:33 PM

Originally Posted by Terry

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-produ...ess-panel.html

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.

**lkstaack** · 05-23-2012, 02:52 PM

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?