cleaning out old pipes
My dad has an old house with old pipes, mostly metal. He's got hard water and uses a water softener (I think it's the Culligan Man). It is a two-story house with a basement. I am sure the pipes are filled with lime. His shower is especially lame, and the dishwasher has begun to not clean so well. No way to run two things at once--even flushing a toilet greatly reduces pressure at kitchen sink. My question is: Can the old pipes be cleaned out in some way? Years ago a guy suggested pouring vinegar in at the service entrance and letting it sit awhile. I have always wondered whether it would work. Is this crazy? What about Lime Away or some similar product? Would terribleness result? I am guessing it would be several thousand dollars to re-plumb the house, so I am looking for a less-expensive alternative. Many thanks for your expertise.