Copper pipe soldering: Flux burns the moment I apply heat

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FreeLander

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Hello,
Beginner here. I have a heat exchanger that has a copper manifold. What I'm planning to do is solder the 1" inlet to a copper to CPV adaptor. Since the heat exchanger is expensive, I decided to buy 1/2 pipes with fittings to practice.

I did prep the pipes well and put a generous amount of flux, but the moment I apply heat the flux evaporates instantly and the solder won't stick. I decrease the heat but the flux just evaporates.

For the torch, I could not find MAPP or Putane so I went with Butane.

What am I doing wrong?
 

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Mr tee

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It looks like you are heating the pipe, you need to heat the center of the elbow.
 

James Henry

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Turn your flame down, it's way to high, then go back and forth over the pipe and fitting with the flame and every few seconds touch the joint with the solder, when it melts to the touch remove the flame and only apply the flame to the pipe when the solder stops melting. after the joint is soldered wait for the solder joint to go from shiny to dull then wipe it down rigorously with a cotton cloth.
Wear cotton gloves when soldering so you don't burn your hands on the hot pipe.
 

Jadnashua

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My preference in flux is a tinning flux. That has powdered solder mixed in. Especially for someone that doesn't do this often, using this type of flux gives you an indication that the material is hot enough because you can see the solder in the flux melt, then quickly adding some more to finish it off.

You want to be heating mostly the fitting and moving the flame around the joint. Solder gets sucked towards the heat. Once the connection is hot enough, you can usually remove the torch, and just run the solder rod around the joint.
 

FreeLander

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My preference in flux is a tinning flux. That has powdered solder mixed in. Especially for someone that doesn't do this often, using this type of flux gives you an indication that the material is hot enough because you can see the solder in the flux melt, then quickly adding some more to finish it off.

You want to be heating mostly the fitting and moving the flame around the joint. Solder gets sucked towards the heat. Once the connection is hot enough, you can usually remove the torch, and just run the solder rod around the joint.
Thanks! but does this flux work? and soldering wire with Butane work if done correctly? Or should I get something else?
 

FreeLander

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Turn your flame down, it's way to high, then go back and forth over the pipe and fitting with the flame and every few seconds touch the joint with the solder, when it melts to the touch remove the flame and only apply the flame to the pipe when the solder stops melting. after the joint is soldered wait for the solder joint to go from shiny to dull then wipe it down rigorously with a cotton cloth.
Wear cotton gloves when soldering so you don't burn your hands on the hot pipe.
Will do! I was worried that materials are wrong? Is this flux and soldering wire with Butane work if done correctly? Or should I get something else?
 

FreeLander

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Turn your flame down, it's way to high, then go back and forth over the pipe and fitting with the flame and every few seconds touch the joint with the solder, when it melts to the touch remove the flame and only apply the flame to the pipe when the solder stops melting. after the joint is soldered wait for the solder joint to go from shiny to dull then wipe it down rigorously with a cotton cloth.
Wear cotton gloves when soldering so you don't burn your hands on the hot pipe.
Btw I did that and kept doing it but instead of the rod melting, it bent! It is harris 0
 

Reach4

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is that 20% tin 80% lead solder? And zinc chloride flux... often that was mixed with hydrochloric acid to make acid flux. Old time stuff. I was thinking that should take high temperatures well.

I don't see that you cleaned the copper well. It should be bright copper color on both sides where the solder will flow. Sand paper, wire brush, etc.

I don't know if more modern stuff would work better.
 

FreeLander

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Guys, I was hoping we can pinpoint the problem. Is it the torch Butane? Solder? Flux?
 

FreeLander

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It's not what your using, it's you, your overheating the pipe. I can solder with any kind of bottled gas.
Good. At least we've established that. I followed your earlier instructions word by word. Kept the torch on its lowest but as I said, the moment it touches the pipe the flux melts down to the floor. When I touch it with the wire it won't stick, because, I'm guessing, there's no flux to guide it through. I made sure the flame is as low as possible!
 

Terry

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Clean pipe and fitting by sanding or brushing.
Flux on inside of fitting and outside of pipe.
Apply heat to fitting and pipe, touching every so often to see if the fitting is hot enough to take solder.

Let set until cool, then wipe the fitting with a rag.
I like to have a spray bottle handy, and gloves. Hot copper will give you a nasty burn if you touch it too soon.
 

James Henry

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Good. At least we've established that. I followed your earlier instructions word by word. Kept the torch on its lowest but as I said, the moment it touches the pipe the flux melts down to the floor. When I touch it with the wire it won't stick, because, I'm guessing, there's no flux to guide it through. I made sure the flame is as low as possible!
The flux is supposed to melt and drip on the floor, do not aim the flame inside the joint, heat the pipe until the solder melts when you touch the pipe. You have to be patient when you solder pipe.
 

Terry

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Oh yeah, make sure you have something to catch the dripping flux.
Nothing like drippy flux landing on your arms. That's why I solder the furthest fitting first and work my way back to me.
 

FreeLander

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Thanks, guys. I'll keep trying with your notes in mind. Appreciate all your help.
 

FreeLander

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The flux is supposed to melt and drip on the floor, do not aim the flame inside the joint, heat the pipe until the solder melts when you touch the pipe. You have to be patient when you solder pipe.
I tried brazing, but the rod bent instead of melted. It is a Harris 0. Would you say a STAY-SILV 15 is easier to melt and braze?
 

JohnCT

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Hello,
Beginner here. I have a heat exchanger that has a copper manifold. What I'm planning to do is solder the 1" inlet to a copper to CPV adaptor. Since the heat exchanger is expensive, I decided to buy 1/2 pipes with fittings to practice.

I did prep the pipes well and put a generous amount of flux, but the moment I apply heat the flux evaporates instantly and the solder won't stick. I decrease the heat but the flux just evaporates.

For the torch, I could not find MAPP or Putane so I went with Butane.

What am I doing wrong?

This shouldn't be that difficult. Being where you are, I'm not familiar with your solder and flux brands, so there may be an issue with your supplies. Perhaps you're doing this correctly and your flux is just burning at a temperature lower than your solder needs to flow. Asking a local plumbing supply where you are may clear up any issue with your material.

Regarding cleaning, do not skimp on this stage. Everything you have read about cleaning pipe is not an exaggeration. Your pipe must be thoroughly abraded with sandpaper, a stiff wire brush, or steel wool so the copper shines like gold - inside and out before applying flux.

Here in the States, most amateurs use a typical propane torch which works fine for 1/2" and 3/4" pipes. For larger pipes, MAPP gas is an option as well, but no matter what heat source you are using, it's very important not to scorch the pipe and flux, or the joints will need to be disassembled and *re-cleaned* with abrasives.

This is a very short video that shows what properly heated pipes and solder flow looks like. You don't need to wipe after you make your joint - that's pretty much for show.


Good luck!

John
 

FreeLander

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This shouldn't be that difficult. Being where you are, I'm not familiar with your solder and flux brands, so there may be an issue with your supplies. Perhaps you're doing this correctly and your flux is just burning at a temperature lower than your solder needs to flow. Asking a local plumbing supply where you are may clear up any issue with your material.

Regarding cleaning, do not skimp on this stage. Everything you have read about cleaning pipe is not an exaggeration. Your pipe must be thoroughly abraded with sandpaper, a stiff wire brush, or steel wool so the copper shines like gold - inside and out before applying flux.

Here in the States, most amateurs use a typical propane torch which works fine for 1/2" and 3/4" pipes. For larger pipes, MAPP gas is an option as well, but no matter what heat source you are using, it's very important not to scorch the pipe and flux, or the joints will need to be disassembled and *re-cleaned* with abrasives.

This is a very short video that shows what properly heated pipes and solder flow looks like. You don't need to wipe after you make your joint - that's pretty much for show.


Good luck!

John
Thanks, John! this is very helpful. Maybe you can help me decide which is better, soldering or brazing, for my application. The reason I'm learning this is that I bought a heat exchanger that has a copper manifold, and I want to solder it to a CopperToCPVC adaptor. One guy on YouTube was struggling with this as too much heat deformed the CPVC end of the copper fitting. Please watch this and tell me what would you do? Would you instead braze it with a Harris 15% to minimize heat exposure? That's what I was thinking, at least. Would love to hear what you think.

 

FreeLander

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The flux is supposed to melt and drip on the floor, do not aim the flame inside the joint, heat the pipe until the solder melts when you touch the pipe. You have to be patient when you solder pipe.
Can you please have a look at my reply to John? I'd appreciate your input. Here
 
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