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Sewer smell after hooking into plumbing vent

9K views 10 replies 4 participants last post by  Plumber101 
#1 ·
I purchased my home 4 years ago and was aware of a prior issue with the existing plumbing vent. The issue is, the previous owner remodeled the bathroom and never tied anything into the existing plumbing vent. I have 1 bathroom with a shower, sink and toliet that are not attached to any plumbing vents.

I can see the existing plumbing vent from my basment ceiling. It is made of copper and goes to the roof. Everyime it would rain, the vent would obviously drip into the basement :)

For the past 4 years I've been too lazy to do anything about it. I have no idea why the previous owner didn't tap into the plumbing vent as the new PVC piping he put in for the sink goes right underneath the existing plumbing vent!!

So, seeing the PVC piping for the sink is right underneath the copper plumbing vent, I went to Lowes and bought a "Y" shaped fernco coupling. My plan was to go to the basement and cut the PVC pipe for the bathroom sink and connect the coupling to each side of the PVC pipe and the plumbing vent.

After struggling with connecting everything, I finally got it all together. However I have an issue. The issue is, I now have a sewer smell coming from my bathroom sink. It was not there before when nothing was hooked up to the vent...but is noticable now that I have hooked into the vent.

I assume this is not normal? If it is, will the smell eventually go away since it has been so long since anything was vented?

One a better note, even though the plumbing vent is hooked into the sink pipe, my toilet seems to flow better now :)...but the smell coming from my sink is pretty bad :(
 
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#7 · (Edited)
Okay, first of all that sink isnt vented...period.

Secondly, the trap on that sink is cocked and probably isnt making a good connection at the tailpiece. Cant say for sure that this is where the smell is coming from, but the picture makes me suspicious. Another possibility is that now that you say your toilet is vented and running better it could be sucking that non vented trap dry. You could add an air admittance valve on there and see if that helps. I dislike AAVs but in this case it might be the way to go.

Did you say the tie in you did was in the basement? If so then you didnt actually vent any fixtures....you vented a horizonal branch drain. Now that isnt necessarily a bad thing....just...well the fixtures themselves need to be vented.
 
#8 ·
Okay, first of all that sink isnt vented...period.

Secondly, the trap on that sink is cocked and probably isnt making a good connection at the tailpiece. Cant say for sure that this is where the smell is coming from, but the picture makes me suspicious. Another possibility is that now that you say your toilet is vented and running better it could be sucking that non vented trap dry. You could add an air admittance valve on there and see if that helps. I dislike AAVs but in this case it might be the way to go.

Did you say the tie in you did was in the basement? If so then you didnt actually vent any fixtures....you vented a horizonal branch drain. Now that isnt necessarily a bad thing....just...well the fixtures themselves need to be vented.
Last night, I ended up removing the connection to the plumbing vent and using duct tape to cover the opening. The smell went away in the sink.

As I stated, none of the fixtures in the bathroom are vented. Looking at all the plumbing in the basement, there is nothing that is attached to a plumbing vent.

You are correct in stating that, in the first picture above, the drainage pipe from the sink is now connected to the plumbing vent (the copper pipe in the pic). I figured I'd hook it up there so at least it is connected to something. However, that backfired on me since the swere smell then came up from the sink. Also, it could have been my imagination that the toliet flowed better since it was late at night and I was tired
 
#11 ·
Ah...yea it isn't vented and when it drains it sucks the water out of the trap weir.

Instead of the 90 to the trap. Cut the 90 off install a "t" plumb in the trap to the "T" on the top of the "T" install an AAV (Air Admitance Valve)

Plumb the trap vertical so there is no cocking to it.

Problen solved.:thumbup:
 
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