Do The Fittings Need To Be Sweated Before Being Installed On Shower Valve? - Plumbing - DIY Home Improvement | DIYChatroom

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Old 08-23-2008, 05:25 AM   #1
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Do the fittings need to be sweated before being installed on shower valve?

I am installing a new shower valve in my bathroom remodel. The shower valve I got is a Moen with threaded connections. Do I have to sweat the 1/2 inch threaded (threaded one side and sweat on the other) copper connections before teflon taping the fitting and installing into the shower valve? Can I install the fittings and then sweat them? I would think that would melt the teflon tape and not be recommended? I am not sure how to keep the shower riser one peice if I sweat the fittings before installing. Any info would be appreciated.


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Old 08-23-2008, 05:42 AM   #2
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what you should do is sweat a 4" piece of copper to the fitting. once the fitting is cooled down install your tape and then install the fitting to the valve body. this way you don't over heat the body melting any O rings inside. do the same for the other side. install the body and then continue from the other end into your water supply, BOB


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Old 08-23-2008, 08:15 AM   #3
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Bob's giving you a good method.

Another method is to remove all the guts from the valve body and solder with the fittings attached. The drawback to this is that the brass tends to suck a lot of heat from the joint, and you can easily boil your flux out before the copper gets hot enough. I usually do what Bob suggested and solder my threaded coupling to a piece of pipe before installing it.

Don't worry about the teflon tape. It can take 600 degrees farenheit, and you're soldering at around 400-500 degrees. You won't melt it unless you actually lay the fire to it.
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Old 08-23-2008, 12:22 PM   #4
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I would always solder the male adapters onto the copper before threading them into the valve. Depending on your stud layout, 4" mau be too short and a longer piece might eliminate a coupling. Each installation is unique in this respect, but the concept is the same.

As for the shower riser, just solder the male adapter on a piece of copper slightly longer then needed and then, after it's threaded into the valve, solder on the drop ear ell at the right distance from the valve.

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Old 08-24-2008, 06:55 PM   #5
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swet the 2 male adpters on to copper nipples 6" and thread them in then continue the piping to the risers...if your concerned on heating the teflon still take a small pipe wrench put in a bucket of ice and just before soldering down from the treaded adapter put it on the adapter where it is will absorb any heat coming towards the teflon...this trick is used with success when it is real tight in the HVAC field with teflon and leak locked threads into something
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Old 08-24-2008, 11:47 PM   #6
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Twightlight call:

If it wuz me, I exchange that valve for one you sweat in and remove the internal stuff from the valve before soldering it in. I just don't trust any connection as much as I do a soldered joint.

Where I live, they don't sell true slip couplings. For some stupid reason, the plumbing wholesalers don't stock them. They only sell couplings that are dimpled, and the plumber's here simply take a half round file and file the dimple off on the ID of the coupling so that it'll slide over the pipe. This is absolutely terrible practice since some of the couplings are punched so har that the dimple depth is darn near the wall thickeness of the coupling. So, if you file that dimple off the ID of the coupling, you have a spot with virtually no wall thickness.

If you have the same kind of couplings, then take a round socket that will fit inside the coupling and hammer on the OD of the coupling to flatten out that dimple so that you don't reduce the wall thickness.

It seems like stupidity on stilts that you can't buy a normal slip coupling in a city with 3/4 of a million people like Winnipeg, but the monkeys that do the ordering for our plumbing wholesalers don't order proper slip couplings because people don't ask for them, and that's because everyone is filing the dimples off the dimpled couplings they sell. It's dumb as a bag of hammers.

Also, here's a good way to check for leaks:

What I do is thread a into the shower elbow a little better than finger tight and solder a Brasscraft stop or just a copper cap onto the pipe for the tub spout. Teflon tape the plug and screw it a little better than finger tight into the shower elbow. Close the Brasscraft stop on the spout pipe. Turn on your water and open the valve handle(s) to allow water into the shower pipe. When water starts to drip out of the treaded plug, tighten it to stop the dripping. Now, close the water shut off valves to your new piping and put paper towels under each joint you threaded or soldered and leave it overnight like that. If there's no evidence of water leakage on any paper towel in the morning, and you get a spray of water when you loosen the threaded plug (meaning it held pressure all night) then you know there are no leaks and you can then button up the wall with confidence there won't be any.

The purpose of closing the shut off valves to the new plumbing is that in the case that something does start leaking after you're asleep, the leak will stop after the pressure in the new piping drops.


Last edited by Nestor_Kelebay; 08-24-2008 at 11:59 PM.
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