Plumbing 101- Pipe Sweating

: I recently extended a line to get water outside the house. I sweated the connections on 3/4 copper pipes. One of the joints has a leak. I have to re-sweat it, but do I need to take it apart, clean it and re-apply flux? Or can I just heat it up and melt the solder onto the original sweat joint. : I did try to reheat it, but the original solder didnt seem to soften. : Any tips for a novice wouls be greatly appreciated. : Thank You! ANY water in the pipe will keep it from getting hot. dont waste time trying to fix it without taking it apart and starting over. saw through the fitting, heat and remove pieces. unless you can be sure the line is open and no back pressure will develope when you heat it, then you want to use a fitting that has a drain on it to allow for the expansion and contraction of air.

: I recently extended a line to get water outside the house. I sweated the connections on 3/4 copper pipes. One of the joints has a leak. I have to re-sweat it, but do I need to take it apart, clean it and re-apply flux? Or can I just heat it up and melt the solder onto the original sweat joint. : I did try to reheat it, but the original solder didnt seem to soften. : Any tips for a novice wouls be greatly appreciated. : Thank You!Depending WHY it is leaking what your able to do. If your leak is from lack of proper Cleaning YOU must cut out this joint and use a Slip coupling. If it was due to improper capillary attraction then use a decent self flux like LACO and and reheat the tubing a little and them more heat on the fitting Apply a liberal amount of flux prior to heating to prevent oxidation. As the solder alloy is drawn in add some more lead free solder. ALLOW the joint to cool naturally. Flush out the excessive flux AND clean off excess flux from out side of the tubing..