Vent pipe leaking and not from rain


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Old 06-21-10, 05:51 PM
J
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Vent pipe leaking and not from rain

I am having an intermittent problem that is baffling me. Granted, I'm not a plumber but bear with me. I own a 2 story home that has two full size bathrooms on the 2nd floor, 1 half bath directly under the shared wall between the 2 full size bathrooms, and then another half bath in the basement. I had this water stain on the ceiling of my main floor half bath and decided to cut a hole in the ceiling to see what was leaking. I found that the subfloor around a particular 1.5" pipe was wet, and after some measuring I determined that pipe went up through the shared wall. I cut a hole in the drywall at this pipe on the 2nd floor, and found it not to be a drain for the toilets or the sinks. It went along the wall at a 45 angle and eventually went up to the attic (after cutting numerous holes in the wall trying to trace the leak). There was a Y fitting midway up the wall that was leaking in what I determined to be the vent pipe. So I cut the old one out and put a new one in. I repaired the drywall but never got around to patching the ceiling. Well yesterday I heard my wife flush the toilet upstairs and then I heard fast dripping water. Yep, the half bath on the main floor had water dripping pretty good from that same pipe. Needless to say either my Y-coupler repair was bad or its now leaking from another location.

My main concern is how is water backing up into the vent pipe? This Y-coupler was midway up the wall on the 2nd floor, meaning there is a few feet of head to push water up that high. She flushed the toilet two more times and each time water came leaking down the vent pipe. Running the water in the bathroom sink or taking a shower did not result in a leak, neither does running the washing machine. I flushed the toilet multiple times today and it is not leaking, so it seems to be a random thing (except when it occurs it happens consistently until it sits for awhile).

For those experience in this area, give me some suggestions or descriptions on how water is backing up into this vent pipe and how I can fix it (with exception to the obvious repair to the Y-coupler). If you need more info let me know
 
  #2  
Old 06-21-10, 07:18 PM
Z
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I find it difficult to believe that it's backing up and dripping out the vent pipe. (not that I don't believe what you've seen, it just doesn't really make sense).

If it was backing up that much, you'd be having all sorts of draining issues, toilet not draining, etc. Are you sure it's dripping out the vent pipe? Could it be leaking at the wax ring or maybe the supply pipe and just following the pipes down?

Maybe a few pictures would help. Also, how did you repair the Wye?
 
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Old 06-21-10, 08:14 PM
J
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thats exactly what I have been thinking! When I cut the hole in the drywall at the wye previously, the downpipe at the wye was wet but was dry above the wye. That pipe went up through the attic and I verified that with a mirror as well as going up in the attic. The wye is eye-level, so probably 2-3' higher than the toilet tank. It is about 2' to the side of the subject toilet as well. From what little I can see in the hole in the ceiling, the drain pipe runs along the floor joists to each side of the house. I don't see any connections to the toilet drain nearby.

The drains all work well and haven't really had any draining issues.

With the hole I have cut in the ceiling of the main level half bath, I can actually see the drain pipe for the toilet that is also connected to the drain of the toilet from the adjacent bathroom. Both of those pipes are about 12" away from this particular vent pipe and are both dry.

After I flushed the toilet numerous times today, I ran down to the main level half bath to listen to the pipes. Probably 30 seconds after the toilet finished filling up, I could hear water trickling through the vent pipe. I'm 95% sure the water sound was from the vent pipe.

I cut out the PVC wye and used couplers with short pipes that fit in the couplers and the new wye section. I have not cut the drywall again to see if it is coming from that same wye again. The next time it leaks I'll be cutting quickly and then flushing again. I just thought I'd post on here to see if anyone else has experienced this, as it just doesn't make sense to me in my very basic understanding of plumbing.
 
 

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