Help! Knocking in vapor system after renovation

lbrickme

Hi all,



I posted a question on the wall several years ago and relayed your expert answers to our not-so-expert plumber.  Following the advice to a tee he was able to handily fix our problems.  (We of course made a donation to heatinghelp.com to express our thanks.) I thought I'd try again to see if I can help a neighbor & myself in the process!



We live in a condo (100+ year old 2-family).  Our neighbors (and thus we via our shared wall) have a knocking problem daily which is especially bad when the heat is coming up.  They had a plumber try to fix it last winter with no success.



Here are the facts:

(a) The house is 3 stories

(b) The steam heating system is a 1-pipe, vapor/vaccuum system

(c) Two years ago they gutted their first floor and replaced the radiators on that floor with a radiant heat floor.  The 2nd & 3rd stories are still heated via the steam heating system.

(d) I believe the furnace has a pressuretrol & 1 main vent (one or both of which may be part of the problem?)



I've included photos of:

(1) a typical radiator in the house

(2) the furnace

(3) the pressuretrol (at least I think that's what it is)

(4) the main vent



Our neighbors would love to fix this problem once and for all, as would we. So we're hoping you can help us out!  Thanks in advance for taking the time to suggest a solution(s).



Thanks,

Laura

Jamie Hall

One pipe?

vapour/vacuum system?  No.  It's a standard (as much as any vapour system is standard!) two pipe vapour system.  No problem there, just for information.



That is a pressuretrol, set as right as a pressuretrol can be.  It probably isn't the source of the problem, so you can live with it -- although a vaporstat would be nice, to control the low pressure you need somewhat better.



Having gotten that much off my chest!



There are two possible sources for a banging right near the beginnng of a heating cycle -- and both may be worst on the first run in the morning, coming out of a setback, so that's no help at all.  Ther first is a water hammer, and the second is expansion of a pipe.



If this began right after the renovation, my first thought, oddly, would be to look for someplace where, during the renovation, pipe supports were changed.  You could be looking for a sag, creating water hammer, but you could also be looking for a place where the pipe is not free to move as it expands.  The two noises are rather different, but until you have heard both it's sometimes hard to tell.  Another possibility is that when the first floor radiators were taken out, support may have changed -- again, look for sags or tight spots.  If piping was significantly rearranged, you should check to make sure that the returns are all pitched correctly, ditto mains, risers... horizontal runouts.  The usual suspects.  One way to tell where the problem might be, by the way, if you have good access to the mains, is to note where the piping is just getting hot when the banging starts.  You can do this with your hand (the old yeouch test).  It will help you figure out where the problem is, although not necessarily what.  I suggest this, because banging can telegraph through the pipes in a most exasperating way.



I might add -- is that the only vent?  Probably wouldn't hurt to replace it with a bigger one -- say a Gorton #2 -- but I doubt very much that it has anything to do with the banging, and if the heat is reasonably quick and even, it's a pretty low priority on a vapour system.



Keep us posted!

Gordo

The Near Boiler Piping

Looks like the installer did not read the instructions.   Hope you got a good price.



It looks like you have a "dry return"  that drops down to tie in to the equalizer line via a Harford loop.



Check to make sure you are not making more than a few oz/in2 of steam pressure, or water will be held up in that dry return.  When the boiler shuts off after a long run, the water may come rushing back and hammer into the left-over steam in that equalizer.

The Steam Whisperer (Formerly Boilerpro)

I noticed....

on the radiator picture that the supply valve looks new and there is not a conventional trap on the return.  If that is just an open return elbow on the return, then an orifice needs to be installed on the supply valve for each radiator so steam cannot make it into the return lines.  Very common problem on vapor systems.



Boilerpro

Unknown

aaaaaarrrrrghhhhhh!!!

Those time we helped you before and you still call the boiler ," furance" !?!!..

Okay that's off off my chest... from looking at the given pictures, the poor Weil McLain BOILER near pipings is incorrect. No minmumim 24 " riser piping before steam main, etc. Wondering if you already gotten the Laosh book from this site?