I've been stripping out the bathroom in our new house today and I've disturbed one of the solder joints on the plumbing so it drips. I've had a propane torch on it for a few minutes but it just isn't melting. The water is all drained. What am I doing wrong?

I've had a thought. It's probably a central heating pipe. I'll drain it and try again.

You need to make sure it's all drained. Any water will certainly stop the solder melting and any new joint from sealing. Make sure you use wire wool to clean up or better still chop back and put new pipe in.

Flux will also help melt the solder, and new joints must have flux applied.

Sorry if you know this already

as above, drain the system (or just the pipe)
then clean it with 'wire wool' or similar.
then to get the solder to flow add some new solder, and some flux
rosin cored solder can be used

Yes, I'll be adding rosin core solder. It's justto stop it dripping. It will be replaced in a few weeks. Whoever fittedcthe bathroom laid the new pipes above the floor then fitted a new floor above that. IIt's all coming out.

it will never solder with water in it, also you say its old , how old? beware of imperial pipe, if its 1/2" a 15mm compression fits, if its old 3/4 not 22mm then you need a 3/4 olive in the compression fitting

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Originally posted by smart51
Yes, I'll be adding rosin core solder. It's just to stop it dripping. It will be replaced in a few weeks. Whoever fitted the bathroom laid the new pipes above the floor then fitted a new floor above that. It's all coming out.

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Little tip I was given a few years ago. Tying to solder a joint and for whatever reason water trickles out of the pipes being soldered, probably water trapped during draining and happens a lot on central heating systems, and so cant get enough heat into the joint.

Solution make a ball of bread paste and stuff it up the pipe, you'll then get a few mins before the water soaks through it to do the joint. Once water returns to the pipe the bread dissolves, job done.

Thanks everyone. It was the central heating. Once drained, it soldered no problem.