This is a simple minded question, but I am a simple guy. I am putting in hydroponic underfloor heating. I finished running the PEX and now I need to run 3/4" copper tubing back to the boilder room, before I call in the plumber to hook the baby up to the furnace. It is about a 25 foot run. The basement ceiling is a cheapo drop down with removeable panels, and no more than 6 inches of space below the joists. Do I build and solder the copper tubes on the floor, and then try to get the long tubes into the ceiling? Or do I mount the tubes with hangers in the ceiling first, and then solder them in place? I have a propane torch and I am afraid of igniting the place.