soldering question

I'm finally getting around to replacing my irrigation systems back flow safety and had a question or two.
Originally I had two atmospheric valves on my irrigation supply line. I've now bought a pressure vacuum breaker. I have everything pieced together and ready to solder.
1) The old setup was all soldered together, no easy break down. I had to cut an elbow to get everything off. Does it matter if I solder it all together again or should I put a coupler in there?
2) Assuming I just solder it all together as is how will teflon tape on a threaded male adapter hold up to the heat of soldering the other end of the same adapter?
Thanks Matt
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Hi, Matt.
Dunno what a "coupler" is. What you removed, you can replace, with the challenge of melting solder while placing fittings. Always: shine the joint faces, and liberal flux.
What I'd use: sweat unions, to enable quick disconnect of sections of tubing. Then you likely don't have to concern yourself with some threaded joints.
I've had taped threaded joints near sweated joints many times, with no failures. Heat it just enough to get the solder to flow, of course.
HTH, J
MattMika wrote:

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teflon tape and high heat - not a good mix

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Yes, I found that out last night. After soldering the pieces together and turning on the water I found one small leak in a sweat joint that I figure I could have just heated again to seal but then realized one of the two threaded joints was leaking. I was pissed, as I have to pull it all apart and try again. Guess I'll learn to sweat a joint better, it didnt work quite as easily as I thought would. A couple joints sucked the solder right up but one or two didnt seem to work to well, fortuneatly only one leaked.
Is there a better sealer to use? One that will take the heat better? Is there some type of sealer I can just paint onto the threads that will seep in and seal it? Thanks,
Matt
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MattMika wrote:

Most likely one of two causes--
1. If old work, some residual water is preventing quick heatup. Solution--drain better or if can't, the old bread trick to act as a sponge is always possible.
2. Missed getting one side or the other of the joint really clean and fluxed. Solution--clean and flux.. ( Doh :) )

Don't know what threaded connection you're talking of...if it's a sweated union, as an earlier poster recommended, the threads have no function in sealing the joint.

Not really.
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Its a threaded male adapter on one end to thread into the vacumm pressure valve and a female sweat union on the other side. The sweat joint got soldered just fine, just enough to destroy the teflon seal on the threads...
The previous plumbing had what looked like a grey liquid seal on the threaded parts. What would this be? Would it stand up better to the heat?
Thanks,
Matt
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MattMika wrote:

Plumber's "dope" -- thread sealant. Will probably be a little more heat resistant. If you got the parts arranged in an optimum order, you should be able to do all the soldering first, then put the threaded pieces together.
Oh, one aside...where did you get the pieces-parts? I've found a lot of the Chinese junk from the local Ace Hardware and equivalents to have such sloppy thread tolerances it wasn't possible to tighten them no matter what...
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that reminds of a funny trick I play on my girlfriends all the time, I cruise by the plumbing supply house and send them in on an errand, I tell them to tell the guy at the counter that "my boyfriend needs some dope"
they think I am crazy!
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After pulling everything apart, cleaning it and resoldering, I finally got it right! It really pays to think about how the pieces go together. Wish I would have put more thought into it the first time, would've saved me a couple hours of heating, cleaning and sanding joints... Matt
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