water in riser....how do i sweat solder?

I want to sweat solder an elbow onto a riser....problem is after shutting of the house water there is standing water to the top of the riser, as a matter of fact is is dripping slowly out of the riser. How do I solder the fitting with water in the pipes? I think the steam will prevent the solder from sticking to the copper.

The slow dripping out suggests that the valve that you used to shut off the water is not fully closing. Repair/replace that first. Then, I'd insert the end of a plastic tube into the pipe and use my mouth to siphon out the water. You cannot solder the fitting with water in the pipe near to where you are soldering.

-Nathan

The shut off valve is working fine. The problem is that the copper is near the floor and the water remaining in the lines after shutting off the man is putting head pressure on the riser.

I fixed the problem: I opened up 2 outside hose bibs and used my compressor to blow out the remaining water throughout the house. It worked perfectly. I've read about stuffing bread into the lines and other novel "tricks of the trade", but I believe shooting compressed air through the line is the easiest and best solution.

Problem solved.

Gravity would have dropped the water level enough after opening a valve down low in the system and the one in question also open - no air compressor required, but it probably sped up the process. Using too high of a pressure, though, could damage some things and loosen more crud that may be in the pipes.

jadnashua said:

Gravity would have dropped the water level enough after opening a valve down low in the system and the one in question also open - no air compressor required, but it probably sped up the process. Using too high of a pressure, though, could damage some things and loosen more crud that may be in the pipes.

Click to expand...

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The riser was at the lowest point in the system and would never have drained. There's no galv in the system so I wasn't worried about knocking crud loose, and at 100 psi and 2 open hose bibs, one upstream and one down stream, I had no concern about damage from the pressure flush. Keep in mind I hand held the compressor nozzle on the riser....if there had been any excessive pressure build up, water would have blown easily out of the riser right past my hand.

Scott:

If you have a wet/dry vaccuum cleaner, you can use construction adhesive to glue a dishwasher bushing:



into the end of a 2 1/2" wet/dry vaccuum hose coupling:



...both of which should be available at Home Depot.

A piece of 5/8" ID rubber hose will fit onto the dishwasher bushing and your wet/dry vaccuum cleaner hose will fit into the hose coupling, thereby allowing you to connect your wet/dry vaccuum cleaner to your 1/2 inch copper water supply piping. Turn on the vaccuum cleaner, open a faucet to let the air in, and suck the water out of the supply pipe.