Venting sink within 16" of vent stack

jefsboys

Hello,

I recently had all the plumbing replaced on the first story and basement level of a 2 1/2 story house. I totally gutted the first story bath so I had open walls and took advantage of that to replace the plumbing back there. The second story bath is directly above the 1st story.

The stack was cast iron and a lot of steel drain pipe. We replaced all we had access to with PVC.

The second story bath has new PVC from the sink down, the toilet down and the bathtub down.

After doing this the slight odor of sewer gas that we discovered when doing the plumbing changes still remained.
This leaves only the 3" cast iron stack from the second story to the roof and a sink vent line on the second story to the cast iron stack to be the culprit.
Please see drawing for details.

Obviously I need to replace some pipe to get rid of the sewer smell. I am not afraid to tear into things but do like to think through and get advice. The house has old wood lathe and plaster so repairs are a little more challenging but not too much. I have done a lot of repairing here so no problem in fixing more access holes wherever needed but again, I just don't want to creating holes if I don't need to.

In the drawing the gray and dark gray pipe are what I need to replace. I have access to the stack from the attic and will have to cut that up in probably two or three pieces to maneuver it out of there.

My question is for the reason that I may be able to change my approach on the fix which would eliminate some need for opening up an access hole.

As indicated in the drawing....
Do I need that vent line from the sink or can I eliminate it?
I know it was there for all these years but that doesn't necessarilly mean it had a functional purpose. With the drain pipes running vertical, then 45, then another 45 and then final pitched to the stack... I don't understand the venting requirements in this case.
Thanks for any input.

Javiles

How do you know the sewer gases are coming that section.. And yes if an active drain you do need that vent may be able to use an AAV, not crazy about them but they do work. Check with your local code to see if let you use them.

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TheEplumber

Every trap needs a vent. Just because you have vertical pipe and 45's doesn't mean you can eliminate a vent. If allowed by your local code, you could use a auto vent perhaps, still need to find the leak though

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jefsboys

Thank you both for your input and time.

The gray pipe on the drawing is the only old pipe left, everything else has been replaced, I guess just kind of bad luck :-).
The smell isn't centralized in the first floor or in the basement(they both were just redone about 4 months ago) but the smell is strong when smelling around the stack as it comes up through the floor in the attic on its way up to and through the roof.

I know that the new pipe could have been installed incorrectly resulting in the odor but that is still open and visually inspecting and the sniffer gives it a pass on the test.

If the venting is definitely needed I will just replace the pipe in the wall.
Like I said I am not afraid to cut open the wall just wanted other advice/input before I began.

Javiles

Find someone in your area that can perform a smoke test. You’ll find any leaks within the venting or drain system. Sewer gas smell.

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jefsboys

I may look into the smoke test.

Not to drag this on and I know there is much on the web about the following but I have read in several places where if the drain is within 5' of the stack that it may not need venting.

I am planning on taking the advice but can someone shed light on this 5' venting requirement? I think I have seen where that distance is a bit different in other areas but 5' seems the number I have seen most.

I am only inquiring so I have a better understanding of this.

mathx

This might be relevant/related. This if for Ontario's code.

page 20-21 http://www.mechanicalbusiness.com/archives/july_2010/

hammerlane

I believe the 5' measurement has to do with the fixture trap arm.

Attached Thumbnails

 

mathx

great diagram - what area's code is that for?

jefsboys

Maybe a little confused here. My apologies for not picking up on this probably as quick as I should.
You are the experts on this so I am just digging a little deeper into your minds. :-)

So if the trap is within 5' of the vent does it need to have that extra vent going up and tying into the vent above?

From a couple responses I see yes and a couple of responses with the diagrams I read those as no.

Maybe I am reading the responses incorrectly.

BTW: There is no local code to follow. 600 person community. I do like to do it right though and go through extra time, cost and sweat to do so.

Thank you,

Jeffrey

TheEplumber

Trap arms per UPC-
1.5" - 3.5'
2" - 5'
Trap arms cannot have vertical offsets. If you are thinking of eliminating the 1.5" vent piping above your lav drain then that fixture will no longer be vented.

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jefsboys

Excellent.
That cleared it up for me. The vertical offset is something I thought was introducing a twist I wasn't aware of.

Really appreciate your patience and explanation.

Jeffrey