Resoldering leaking joints?

Hi,

After checking over all visible CH pipework I have located two leaking solder joints. How to repair them? Is it possible to just resolder them after draining down CH system. If yes, what is the best way to do it? I have searched the net but all available info is mainly about soldering not resoldering.

Thanks in advance

Rafal

Reply to
Rafal
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If you are going to drain down the system, then you may as well do the job properly and remake the faulty joints by cutting out and using new fittings.

S'pose you could try brushing active flux around the joint and heating it up...

Lee

Reply to
Lee

This can only be done if you can get rid of *all* the water lying in the adjacent pipes. If one of the runs is horizontal and can't be moved you might find this difficult. If they can be unclipped and raised slightly so the water runs away if will be possible.

However, if the joint has leaked because the pipe or fitting was dirty, your only safe option is to separate it and start again - it's usually possible to pull them apart with grips after heating.

If you made the joint yourself, and you know it was clean and properly fluxed, and simply 'dry' then applying more flux and solder *may* work.

When heating a solder fitting, move the blowlamp about to heat it as evenly as possible, and if an end feed type try and feed in the solder from the least accessible point - ie round the back - so you can be sure it's melted throughout.

Reply to
Dave Plowman

The problem is you don't know what state the copper is in - chances are it never soldered properly in the first place because of inadequate cleaning/fluxing, and further heating will only oxidise it more, so it would be safest to redo the joint from scratch - saves the hassle of refilling only to find it still leaks. If you really don't want to replace, put plenty of flux around, heat and apply plenty of fresh solder all round each end. Remember solder flows towards heat - this can help in getting solder to the right place - ensure you heat both the pipe and the joint for best chance of good flow.

Reply to
Mike Harrison

"Rafal" wrote in news: snipped-for-privacy@uni-berlin.de:

Yes, get the pipes perfectly dry. If there are taps or valves in the pipes open them, as hot expanding air will blow out the joints as well as steam will.

You may not be able to get the fittings off, depending on the play in the pipes, if not cut out a section and put in a new bit, or better (just more upmarket) replace the whole pipes section.

Unsolder the joint by putting blowlamp on and wiggling tii it comes free.

Wipe the joint while hot to remove solder, then wirewool it till perfectly clean, also the inside of new fittings, and flux all surfaces.

IT CANT BE TOO CLEAN OR TOO NICELY FLUXED - it's the one secret.

Make the joints - is the pipe still dry, are there any closed valves? - then heat up with blowlamp. DON'T OVERDO IT.

As soon as the solder on a Solder ring fitting runs and gives a nice meniscus, feed a bit in the end for luck, it'll help to be sure the joint is right up to temperature, or endfeed solder if it's not a solder ring.

REMOVE HEAT AND GO AWAY - seriously do not wiggle it to see if it's fixed, because then it won't be.

If you're not confident practice on a couple - unsolder them too, and see if you had a nice even coating of solder when the joint was made.

HTH

done a million and not all that many leaked mike

Reply to
mike ring

If a soldered joint leaks, it's usually because the pipe and/or fitting was not cleaned adequately. It is very difficult to correct this later - and you would have to take the joint apart, anyway. It is very difficult to take a soldered joint apart once it has had water in, even if you drain it, because the slightest amount of water will stop it getting hot enough to melt the solder.

The best solution is to cut the pipes either side of the fitting, use a new fitting, and couplings to join new pipe on between the cuts and the fitting. Make sure everything is scupulously clean, and use flux when you re-assemble. Some people swear by end feed fittings, but I always use Yorkshire fittings (with solder rings inside the fitting) plus a powerful blowlamp. Heat until a complete ring of solder becomes visible on each pipe.

Reply to
Set Square

A good builder mate of mine - now retired - also swore by Yorkshires. But also added some solder. He is Irish, if that helps.

Reply to
Dave Plowman

I first read that "by" as "at"...

Somewhat defeats ths object doesn't it? I much prefer end fed if only because you don't get that ugly bump.

Reply to
Dave Liquorice

Quite likely too.

To say nothing of the considerable saving if you're doing a few.

Reply to
Dave Plowman

Yes.

Flux em, heat em, and add solder.

If they are so bad that doesn't work, cut the whole lot out and replace.

Reply to
The Natural Philosopher

Just a little plastic blasphemy. The two problems you have either with redoing the existing joints or soldering in new fittings are a) unless you get the pipes totally dry you will have a problem with getting them to solder at all (the water takes the heat away from the joint) b) as everyone says you will need to flux the joints and flux and central heating doesn't mix all that well as most fluxes are corrosive and should be flushed out of the system before filling it.

An alternative fix is to cut back to the copper pipe and remake the joints using pushfit straights/tees/whatever it is that's leaking. If you think you can work quickly and get the replacement section ready you could just get a big catch tray and do it without fully draining the system (use speedfit end caps to seal the pipes immediately after cutting and then whip the caps off and put the new section in). If it's in a sensitive area (e.g. nice carpet) go ahead and drain down but by using pushfit you will still avoid getting flux in the system or making more bad joints. If you use some of the cuprofit (or similar)copper/brass fittings (available from screwfix or B&Q) then the earth bonding of the pipes will be retained. If however you use plastic like speedfit or Hep2o then you ought to tag the pipes either side of the joint and bridge it with earth wire.

If you push the pipes properly home into the pushfit IT WILL NOT LEAK. There are others on this site who may think they now differently but mostly they're just wrong or misguided or have shares in copper mines!

Have fun,

Fash

Reply to
Stephen Fasham

Neither will a properly done solder joint, and I know which one I'd trust in a concealed location. Any push fit connector relies on a flexible seal. Just how long this will last under continual heating and cooling is anyone's guess. But the life of a solder joint should be long enough for most.

Given that push fit piping and fittings of any sort are more expensive than end feed copper, I'd say the boot is on the other foot.

Reply to
Dave Plowman

I'd say that's very good advice. Two more tips:

  1. I was told that when you have cleaned it so you can see your face in the copper, then also file away at the end face of the fitting to get it really really clean. Also scratch the pipe round with a sharp nail to give it a 'grove' to take the solder. Maybe belts and braces but it worked.
  2. Don't do what I did - kept feeding solder in to make absolutely sure that it was well and truly done. It resulted in lots of solder the consistency of wire wool inside the pipes which blocked up the taps once I turned the water on. Just put enough to 'wet' the end of the joint.

Good luck Phil

Reply to
P.R.Brady

Absolutely no need - and a deep scratch will spoil the molecular bond of solder.

Just clean it with wire wool until it looks bright and use a decent flux.

If you haven't done end feed before, practice first on scrap - the pipe and fittings are cheap enough - and take one apart after soldering. A well made one will be tinned over the entire area.

Reply to
Dave Plowman

Thank you very much for all advice. It definately looks like cutting out old fittings and soldering new ones. Thanks again Rafal

Reply to
Rafal

Thank you very much for all advice. It definately looks like cutting out old fittings and soldering new ones. Thanks again Rafal

Reply to
Rafal

I don't tend to have any problems with straight or elbow connectors but I have a very poor success rate with t-joints, to the extent that I have started using compression fittings instead. Is anyone aware of any reasons why I shouldn't mix and match compression and soldered fittings in this way ? Can anyone suggest what I might be doing wrong when attempting to solder t-joints ? I often end up with one out of the three connections leaking.

Reply to
Kevin

I'd say the likely cause is you're not moving the flame enough to heat the entire thing evenly - or using too small a flame. If you strip down a faulty one, are all the surfaces properly tinned?

Reply to
Dave Plowman

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