Yes, ours is a single-pipe system delivering steam.

But what do I do about the "knocking" problem?


"Bubba" wrote in message
...
On Sun, 06 Jan 2008 15:48:39 GMT, "Ray"
wrote:

Sorry to be such a pest, but I have another question about our aging steam
radiator system in our six-unit apartment building. Last night, an hour or
so after the weekly flushing of the systerm, we heard a very loud knock in
the pipes. As if someone had hit the pipe with a sledgehammer.

Is this dangerous? What should I do? Was the knock, which we heard only
once, probably tied in with the flushing?


You most likely have a one pipe steam heating system. The "knock" was
steam hitting the cold condensate water coming back the same pipe.
Yes, it can be VERY destructive.
Bubba