Going crazy trying to solder copper tubing

I am trying to join two twenty-five lengths of 3/8" od soft refrigeration tubing to make an immersion wort chiller and am not having much luck.

I clean the ends of the tubing with emery cloth until shiny, ditto the inside of the coupler, apply flux to all surfaces to be joined, wipe excess flux, torch the coupling with a propane torch for about 30 seconds until I get a green flame coming from the other side of the coupling but when I apply solder, it beads and does not run into the joint.

I have gone through six couplers and twelve bum joints and know my limits. Before I take the pieces of tubing to a plumber, are there any other ways of joining tubing to make a leak proof fitting? The only alternative I can think of is a compression fitting which I'm not convinced would be leakproof over time. Plus it has nooks and crannies which might make the joint hard to clean.

Or should I forget about joining tubing to make a wort chiller and just bite the bullet for a 50 foot coil? Even with a good brazed joint, there might still be some twisting on the joint as the cooler is moved.

Thanks...

I had this problem when I first started to solder. I then applied enough flux to protrude outside the joint. (Maybe 1/8".) Heat up the section and hit the exposed flux with the solder and the solder will get pulled into the joint.

your not getting the copper hot enough. Leave the flame on the copper until it flows, then pull the flame away

Jaybird said:

your not getting the copper hot enough. Leave the flame on the copper until it flows, then pull the flame away

Click to expand...

No he's getting it to hot and burning all the flux out. Get the joint hot (not burning grean though) and with the heat still on one side put the solder to the top of the joint (have the flame on the side of the joint) as the solder melts the flux will pull it into the joint.

FSR402 said:

No he's getting it to hot and burning all the flux out. Get the joint hot (not burning grean though) and with the heat still on one side put the solder to the top of the joint (have the flame on the side of the joint) as the solder melts the flux will pull it into the joint.

Click to expand...

Yep. When I was first learning to sweat joints I'd overheat them too, drove me nuts. Try it again, you can do it.

[ame=http://www.youtube.com/watch?v=PKKMA4NOaQ4]YouTube - Easy Copper Soldering[/ame]

Your way too hot, just after the flux starts to boil with heat applied to the coupling you should start to apply solder at the joint. When it starts to melt it will draw in the solder at that same time remove the heat and reapply heat in short couple seconds at a time at the most. By now you will have a partical drop of solder on the bottom of the joint, a damp rag wipe on the joint to remove this hanging drop for a professonal clean and sound solid looking joint while the solder is still fluid.
In your case you'll have to sand the copper and coupling copper bright again to remove all that oxidized copper coating before adding a small smear of flux on the tube and inside the coupling.
We are talking about soft soldering here not silver soldering correct?

BrewBeemer said:

We are talking about soft soldering here not silver soldering correct?

Click to expand...

Right... Lennox solder made of tin, copper, selenium

The thing is, I keep running out of couplers as I screw them up. The tubing isn't so hard to clean once I screw up a joint but its a bear cleaning the inside of the couplers. Wrapping the emery cloth around tweezers helps...

Could the flux be boiling/burning away from too much heat?

I have a acetylene torch that gets a joint to hot in no time. I was soldering a 2" tee and had cleaned and fluxed all joints. While soldering one side I boiled the flux out the other and could not sweat that side at all. When I tried to pull the joint apart I couldnt, probably oval pipe to start. Solution was to heat the joint and keep applying flux to it, the flux boiles as soon as touching the pipe, but eventually sucked in enough solder that I made a good joint. Instead of emery cloth and tweezers you might consider a brush made for cleaning inside of fittings, there cheap.

Try to apply the heat a little further away from the joint for a short time before hitting the fitting. You certainly don't want to hit the flux with the flame, it will just burn off. The other thing is, you probably have some halfass water soluable flux which seems to be the norm at the home centers. I hate that stuff and have a lot better luck with acid paste.

somecallmetim said:

Yep. When I was first learning to sweat joints I'd overheat them too, drove me nuts. Try it again, you can do it.

Click to expand...

+1, definitely overheating the joint.

What I do is hold the solder the the backside of the joint while I heat the front side. The solder will wick as soon as the joint is hot. A plumber showed me another trick on larger fittings: Make a 1/2 loop of solder by wrapping it around the pipe, kinda like a shepard's staff. hold that against the backside while heating the front, keep the flame moving. The solder should all melt at once and wick into the joint.

Soldering is fun but takes a little practice. Once you get the hang of it, it's cake though. The too easiest mistakes are too much heat and too much solder.