adding vents?

mor

In a three floor house with a one pipe system, a single header in the basement, branching into several risers each feeding a rad on each floor. these risers are vented only by the rads. there is a bad hammer problem on cold start. Suggestions??

Unknown

Water Hammer

Is your piping insulated? The hammering at the beginning of the cycle can be from steam hitting the cold piping and collapsing. Here's a link that may be of help to you. - Rod  http://www.heatinghelp.com/article-categories/16/Steam