Clearing Water Lines With a Shop Vacuum
If you have trouble sweating plumbing lines because of residual water in the line, shut off the water main and open some faucets to drain most of the water.
Clear Water Quickly
If you have trouble sweating plumbing lines because of residual water in the line, shut off the water main and open some faucets to drain most of the water. Then attach a wet/dry vacuum hose to the end of the pipe with duct tape and suck out the remaining water. The dry pipes make soldering a breeze. — Kurt Gonzales
How to Use Water Hammer Arresters to Stop Banging Water Lines.