Copper Pipe Soldering Problems - "Pooling"

14 Feb 2007
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United Kingdom
Hi. I'm having some problems soldering some coper pipe (we've had to move some radiators). It's not a task I've done before, so I've spent a lot of time reading up on the topic and watching videos (I know there's no substitute for practice, of course).

I have a Propane Benzomatic torch, with lead free solder & flux. Following advice, I'm wire wooling the ID & OD of the pipe and fittings, although I am using new pipe, so I'm not cleaning up old stuff (yet). Once roughed up, I'm applying flux to the joints, assembling and twisting. Then, I'm cleaning excess flux away and heating the fitting with the blue inner flame.

The flux boils and smokes within about 5secs of heat application, but it takes a good 30secs longer for the fitting to get hot enough to melt solder (flame removed) and the fitting stays hot enough to melt the sodler for about 5secs.

My problem is that the solder just pools up at the mouth of the fitting and drips off the pipe, it never "sucks" into the fitting :mad: I don't know what I'm doing wrong, any advice?

I'm solding 15mm & 10mm pipe with new end-feed fittings on a heating system. Could it be the flux / solder? Should I go and get some leaded stuff (some folks say it's easier to use)? Or is it a technique thing (probalby, as I'm a novice!!)?

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how much heat and where to apply it comes with experience. Use as little heat as you can and heat where you want to solder to run to (the fitting). Any water in the pipes and it won't solder they must be clean/shiny and only flux the pipe, never flux the fitting.
If there's water in the pipe it will never solder.

As dm said flux the pipe, push it together and apply the heat to the fitting.

I always dip the solder in the flux as well.
You're doing it wrong.

This is my method.

Wire wool the outside of the pipe and flux, wire wool the inside of the fitting (you may want to do the outside rim aswell) and flux the inside of the fitting.

Push them together and dont wipe away any excess, now apply heat with a small/medium heat on one side of the the pipe untill the flux boils, keep the heat on and in couple of seconds start gently offering up the solder, if it dosn't melt take it away and try again in a couple more seconds.

When it melts keep the flame on and feed solder in, the amount is practice but two much wont really harm the joint, it will just run out.
Get ready if you want with a damp cloth to wipe away any excess. Leave alone untill cool.

I meant the op is doing it wrong, I replyed as first poster!
I'm only a DIY'er and it seems the pro's don't flux the fitting, I'll have to try that. :)
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Cheers for the quick replies. These are new pipes, I'm sub-assembling before fitting to the existing pipes, therefore, no water anywhere!

I'll try the tips on only fluxing the pipe, not the fitting and I'll move my torch closer to the mouth of the fitting (I was heating further down the fitting, so as not to over heat the pipe). Interesting tip on fluxing the solder, what does that do to help?

Sorry to but in but why is the forum clock an hour slow? I make it a quater to six. :confused:
30 seconds is far too long, the flux will have burned away by then.
I'd recommend you do 1 of these 2 options:
Take some bits of pipe and fittings and practice until it goes smoothly.
Get a pro to do it.

I know we are in a recession, and everybody is trying to save money, but if one you joints pops after a couple of days, the damage will cost a lot more than the money you saved by diy-ing.
JayJay, Doitall & Dangermouse - thanks for the advice, I've just made a lovely leak free sub-assembly! I'll complete the rest of the job tomorrow.

Bengasman - your advice on trying with scrap pipe is good, thanks. However, "get a pro to do itl" was slightly less constructuve, like many other novices, I posted here as I have quite a few joints to do and wanted to learn, not just open my wallet (that's the easy way out!).
No, JayJay you don't flux the fittings, and Yes JayJay you wipe any excess off with a damp cloth before you solder.

Not that any of you lot use it but don't wipe the excess off with Yorkshire traditional flux :rolleyes:
Hi doitall

As you know I made it clear to the op that I was a DIY'er and I was describing the way I did it.

But I remember a plumber telling me how to solder etc and he said always clean and flux the fitting, its just something I've done from then on and its always worked.

Just looked on youtube (not real world I know) but they all said flux the fitting as well as pipe.

Just out of interest whats wrong with fluxing the fitting?

Edit: I'm sure you're right so I'm off in the gararge to test, if I can find some pipe & fittings.
I'm curious too - I was told to flux the fittings (with a brush) and twist pipe in. What's the problem with it?

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