hey plumbers - septic smell

[bughunter]

barndo
small bathroom with sink shower and toilet
the vent was not extended above roof line when i purchased the property and we always had a septic smell. since hiring a plumber to extent the vent stack the problem persists.
could the smell be coming from elsewhere ?
such as the wax ring ?
any help is appreciated.



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[MadHatter]

Could possibly be bad traps, or no traps. Only so many ways smell can get back in.
Wax ring is a possibility as the trap in the toilet is generally the only one you have at that location.

[BrianL]

It is probably coming from your HVAC drain being plumbed into the sewer vent, or the actual sewer vent not being above roofline.

Not a plumber, but a barndo owner. I had to fix both for the same issue

[bughunter]

the remodel included a new toilet so i’m gonna rule out wax ring
but the ac guy did route the drain into the plumbing vent stack
ill move it back outside and see if that corrects the problem

much thanks
happy new year


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[meltingfeather]

smell is only in the bathroom or elsewhere too?
does the bathroom get used? dry traps would be the first and easiest thing to check. could be wax ring too. it's easy enough to replace but nasty!

[meltingfeather]

a/c drain is likely candidate. better to put it outside than trap it because they tend to get clogged with lint and/or slime and folks don't usually maintain that line.
i pour a cup of vinegar down it every time I change the filter to keep it clear.

[BrianL]

the remodel included a new toilet so i’m gonna rule out wax ring
but the ac guy did route the drain into the plumbing vent stack
ill move it back outside and see if that corrects the problem

much thanks
happy new year


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I put a shut off in mine. during the winter, I shut it off because the p trap will dry out, then in summer when using AC I open it back up so it can drain out. Probably going to route my drain out the side this year and do away with that problem.

[MadHatter]

It is probably coming from your HVAC drain being plumbed into the sewer vent, or the actual sewer vent not being above roofline.

Not a plumber, but a barndo owner. I had to fix both for the same issue

Sewer vent above the roofline has nothing to do with venting mechanics.
Lotta BS codes surrounding vents, but the actual mechanics of it, could care less about your roofline. I've taken many of them out the side wall of a house, and they work just fine.

[BrianL]

the remodel included a new toilet so i’m gonna rule out wax ring
but the ac guy did route the drain into the plumbing vent stack
ill move it back outside and see if that corrects the problem

much thanks
happy new year


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I put a shut off in mine. during the winter, I shut it off because the p trap will dry out, then in summer when using AC I open it back up so it can drain out. Probably going to route my drain out the side this year and do away with that problem.

[Monark]

Sewer vent above the roofline has nothing to do with venting mechanics.
Lotta BS codes surrounding vents, but the actual mechanics of it, could care less about your roofline. I've taken many of them out the side wall of a house, and they work just fine.

I agree. I think the purpose of the vent is to break a vacuum so the toilet, tub, sink etc can go to the sewer.

Try this. If you have a clean out hub outside the building, drill an 1/8" hole in the top of the removable cap. If the bathroom is not properly vented, a flush of the toilet can pull a vacuum & empty the sink P trap.

[bughunter]

the smell was everywhere before extending the vent
now only in bathroom and not everyday
just
mostly on calm humid days.


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[BrianL]

Sewer vent above the roofline has nothing to do with venting mechanics.
Lotta BS codes surrounding vents, but the actual mechanics of it, could care less about your roofline. I've taken many of them out the side wall of a house, and they work just fine.

That's not exactly true with metal structures. I learned the hard way. It will vent correctly but the septic/plumbing exhaust travels up the side of the wall and back into w metal structure where roof meets the wall. Rooflines are not airtight on metal unless it was spray foamed encapsulated inside against metal.

[riverbowman]

Drill a 1/4" hole in the wall the vent stack is in. Stick your nose up to the hole and smell it. If the smell intensifies you have an issue with the pipe. Someone could have drilled into the pipe, it could be separated or cracked. We've found this to be the issue many times in construction when all of the common stuff like wax rigs, dry traps are ruled out.

Also, humidity intensifies odors.

[MadHatter]

That's not exactly true with metal structures. I learned the hard way. It will vent correctly but the septic/plumbing exhaust travels up the side of the wall and back into w metal structure where roof meets the wall. Rooflines are not airtight on metal unless it was spray foamed encapsulated inside against metal.

Yes, code covers all this as far as how far from a eve, window, etc., etc...because
you are 100% correct the smell can go wherever it pleases once it leaves the vent, even back inside depending on drafts etc..
If his is through the roof though its seems unlikely .

[double bogey]

This is the reason code doesn't allow a/c drains directly to sewer. Approved locations are under a sink before the trap, and at the washing machine drain before the trap.
With a gas furnace, the coil and drain is in a positive pressure location, and odor isn't as much of an issue. With heat pumps, and electric heaters, the drain is at a negative pressure location. So as your trap dries up, the system pulls air in through the drain.

You can run it outside to water the flower bed, its not code, but its safe. We used to do a lot of French drains with a flue pipe and pea gravel if you don't want it running over the ground.

I have been involved in chasing down sewer smell in a few buildings. Every time, we found a dry trap, a broken pipe, or a pipe someone cut and didn't cap.

If you have a floor drain that doesn't get used, and dries out, use food safe anti freeze, or something septic safe that wont evaporate.