copperplumbingrepair
I need to remove a section of 3" copper, and replace it. Has anyone ever done this with a single Mapp gas torch? I'm not sure if its going to have enough heat to get it done. I probably could get it out without too much of a fuss, I just want to have a bit more confidence I can sweat the new one back in without making a mess.
I'd think it could be done with a pair of Mapp torches, but its probably generally done with acetylene?
Just heat the joint up with your torch, once the solder starts to melt use Channel locks to pull the fittings apart. Once the joint is apart, wipe as much old solder off as you can with a rag. Now you can start over. Clean, Flux, solder.
You should not be applying flux to joints you are not working on, take each joint one at a time. If the joints are all close to each other, try doing the joints out of order. Solder one joint, then move to a joint further away, then back to a joint near the first, etc. This should allow some of the heat to dissipate, and reduce the chances of overheating the joints.
Don't forget to wipe excess solder off the joint before it cools using a damp rag, nothings worse than an ugly joint (except maybe a leaky joint). And don't forget, soldering pipes is an art. And like most things, it takes lots of practice to get good at it.
I agree with the comment in that its surprising the copper pipe would conduct enough heat to freeze the downstream pipe, are you sure there's not a draft or something like that?
Your idea to isolate the pipe seems relatively sound though. You would likely want to use PEX instead of PVC. PEX normally requires a special tool to crimp the connectors, so I would recommend using a SharkBite push-in coupling fitting to connect the PEX to the copper and vise versa as these don't require any special tools to install.
From http://www.sharkbite.com/product/couplings/
SharkBite is the Push-Fit connection system that is really taking hold. It’s the easiest way to join copper, CPVC or PEX pipe in any combination with no soldering, clamps, unions or glue. Just insert the pipe and the stainless steel teeth bite down and grip tight, while a specially formulated O-ring compresses to create a perfect seal.
I don't have any affiliation with SharkBite, they are just a well known brand of push-in fittings. Your local store might have other brands too
Best Answer
You might have luck using two brazing torches, like these. My concerns usually aren't about making a mess; it's getting it to work without burning holes in it and physically getting it back together after a de-solder. I'd start over, but it's worth a shot on a $20 fitting. I'd say my re-solder success rate is 50\50 without doing more work than just using new, clean fittings. I've never done 3" and I wouldn't without a wrap-around torch head for an acetylene kit.
These brazing heads really are nice and make quick work out of plan old soldering.