I have a section of my plumbing which is exposed to freezing weather. It has survived for the last 15 years with the worst situation being that the water froze (and stopped flowing) but didn't break. One thing I had done to prevent freezing is to put heating tape on the hot and cold pipes, inside foam insulation.

A couple of weeks ago, I was not home but had some guests who called and said "they had no hot water". It turns out that the hot water line was broken and so much water was gushing out that there was no hot water for the rest of the house. This break was in the portion of the plumbing which is outside. So I had them turn off the water to that segment.

Today was the first time I was home and investigated, and it turns out that a soldered joint gave way. What is the best way to reattach it (it's a copper fitting). The pipe section is fairly inaccessible, so what's the best way to prepare it for resoldering?

I had installed a GFCI receptacle inside this same cavity into which the heating tape was plugged. I don't know if the heating GFCI had tripped, causing the pipes to freeze, or the water from the leak caused the GFCI to trip. I'm going to replace the receptacle with a weatherproof one which is not GFCI.

BTW, I'm selling this house, and need to solve this problem in a more conventional way.