Noisy pipe

ansky

I need help with some ideas on how to quiet a noisy pipe. The pipe travels up to a 3rd floor bedroom at about a 60-degree angle. Every time the boiler comes on the pipe makes a banging noise for about 30 seconds. This is a problem since it's a bedroom. Any ideas on how to quiet this down? One problem is the pipe is uninsulated, and it's enclosed inside a wood frame to hide it as it goes up the stairs.

Jamie Hall

Not that it makes much difference,

but is this one pipe steam or two?



The problem is almost certainly a water hammer.  That much uninsulated pipe is going to condense a lot of water right at the beginning of the cycle.  The question is, where does the water go?  Several possibilities.  First, is the pipe big enough?  I'd size a pipe like that as a runout, not a riser.  In fact, if I knew it was not going to be insulated, I'd go a size larger yet.  Second, there are two possible places the water can accumulate: at the bottom, which is logical, and at the top, which doesn't sound logical but could happen.  What happens at the bottom of the pipe?  Is there a horizontal runout from the main?  If so, what's the pitch on that?  Is there -- worse yet -- a horizontal runout, a 90, then another 90 to go up the stairs?  I'd want -- again -- a bigger than normal pipe, if that were the setup, and a good pitch on the whole arrangement.  There is also the possiblity that the water is being blown up the pipe (don't laugh) and accumulating at the top -- again, in a horizontal section if there is one.



Either place is going to go whang with some vigour.  The cure, then is to make sure all the pipes are big enough and have a really good pitch to them.  At least, one hopes that that would be the cure... it's where I'd start, anyway.

jpf321

history of the bang...

has it always banged?

just started banging?

new pipe?

anything changed in recent memory?

ansky

Always

The pipe has always banged. It looks like maybe a 1.5 inch diameter pipe.

The pipe comes up through the floor at 90-deg, then runs parallel to the floor (slightly pitched) for about 3 feet, then goes up the stairs at a 60-deg angle, then back to parallel (slightly pitched) at the top of the stairs.

Jamie Hall

And where does it go...

from the top?  And how does it make the about 60 degree angle?  At both the bottom and the top?  That's not a common elbow angle... The bottom connection certainly could hammer, particularly if there isn't much pitch on the horizontal runout to the connection there.  The top could also, depending on how it was piped from the top on to where it ends.



Are you measuring that about 1 1/2 inch diameter as an o.d.?  Because, if so, it simply isn't big enough to handle its own condensate when the system starts.  Been there, done that.