Vent Overflowing Water?

JohnLaPlante

OK, so something is really weird with my system.



I had a HVAC guy out, talked to him for about 30 minutes on the phone before inviting him out to install my new Gorton #2 vents.  Seemed to really know his stuff, knew about my Mouat system, etc.  So after walking all around my system, he notices that my near-boiler wet return piping is corroded and in bad need of replacement.  He asks me how much do I drain the wet return to which I reply, honestly, "Well...I never have in the 7 years I've lived here."   Never knew I needed to do it, honestly!



So we walk around the plant again, and he finds a place where he thinks there should be a vent.  So he spins off this pipe nipple from a "T", and installs one of my spare Gorton #2.  As the pipe comes off we hear gurgling and bubbling of water...he tells me that this is because we just broke an air lock, and that should really get the system humming. 



So we turn on the system, and the vent completely overflows with cold water!  As you can see from the diagram, this vent is well above the water line, in the rafters of the basement (maybe 4' above the waterline).  We quickly turn off the boiler and put the pipe nipple back in place. 



So...is this a sign that my wet return on this side of the basement completely blocked ?  I was planning on having the near boiler wet return/hartford loop piping replaced in the summer, but now it looks like it will be the entire wet return.



Thoughts?  



Thanks, all!!

Jamie Hall

Making the assumption...

that rust brown is supply, green is dry and blue is wet -- your guy is absolutely right, you do need a vent there.  (I am curious, though -- there is one rectangle with both green in and out -- whazzat?  Also, it looks as though you have a wet return cross just above (in the diagram) the vent in question -- is that really a pipe cross, or is there no connexion at that point?).



It is quite possible that the wet return on that side is plugged, although I would expect that in that case you might have some really odd problems with either venting or condensate return -- or both.  Or water hammer.  What is the pitch on the various pipes?  Which way do they flow?



And did the cold water overflow immediately on startup, or did it wait for the boiler to develope a little pressure?

JohnLaPlante

Return Radiator

Jamie, good eyes!



That rad is on the first floor. It is fed by a pipe that is coming down from the second floor. Since all of the pipes are under the floor, i can't tell how it is fed...I'm only assuming it is a return line. The rad does not have a steam supply valve...the pipe just runs in to the bottom of the rad...very strange.



The green line above the vent is not connected there...it is connected to the dry return over by the boiler.



Great question on the pitch...I will check that tomorrow morning.



The cold water appeared well after the boiler had started up...the mains were venting when my wife heard the water dripping and yelled down to me...



Thanks for your post...I really appreciate the help!!



John