Sewer gas smell in Bathroom - complicated

[Mike-L]

Greetings all! New to the forum and I'm hoping you all can help me with a plumbing problem. I have a vacation house out in a rural area of WV. The county requires builders to get a permit but they do not have inspectors nor do they required 3rd party inspections. Here is the situation:

• 3 story, 4 bedrooms, 3 baths. One on each level.
• There is a bad sewer gas smell in the upstairs bedroom after someone uses the shower downstairs or upstairs. This only seems to happen during cold weather.
• I plugged the shower, bathtub and sink drains and ran the shower downstairs. The smell was there and the smell seemed to be the strongest near the toilet.
• There is no vent outlet through the roof, but there is a 2" pipe that goes through the exterior wall in the bathroom which I think might be the outlet. It extends about 12" horizontally. The vanity sink vent goes into the same wall but 4 feet lower than the thru-wall pipe.
• I don't know if there are any Studor vents in the house.
• I've been told that the wax ring is likely the culprit, but if so, why wouldn't the smell be present during the warmer months?

Any ideas?

 

[Twowaxhack]

Reset the toilet and see if the smell goes away. Wax seal costs $2.

 

[SHEPLMBR]

Worse in the winter? Put a 90 on that pipe that goes out and take it up a bit. Inspection or not, plumbing vents should not be terminated horizontally.

 

[Mike-L]

Reset the toilet and see if the smell goes away. Wax seal costs $2.

Thanks, yes that's part 1 of the plan. But it doesn't make sense to me that if this were the problem why it doesn't ever stink in the summer.

 

[Mike-L]

Worse in the winter? Put a 90 on that pipe that goes out and take it up a bit. Inspection or not, plumbing vents should not be terminated horizontally.

Thanks, I will suggest this to the plumber. Can you explain to a "civilian" why terminating horizontally might cause this issue?

 

[Mike-L]

The vent pipe exiting the house is also only 2-2 1/2" or so. Is this enough for 3 bathrooms and a kitchen? If not, could adding Studor type vents at the toilet or other fixtures help? Thanks again!

 

[Twowaxhack]

Thanks, yes that's part 1 of the plan. But it doesn't make sense to me that if this were the problem why it doesn't ever stink in the summer.

I hear all kinds of theories in my day to day and things like “ it only stinks ______” fill in the blank.

Start with a common source of stink from a plumbing system. The toilet wax seal.

 

[Mike-L]

Well, it turns out in this case the problem was indeed the most likely one. Someone had installed a wax ring with a horn that was too big to fit into the flange. The horn allowed the excrement to pass into the drain, but didn't allow a proper seal against the gas.

What are the horns for anyway?

I'm still going to extend the vent pipe up a couple feet next spring as I think that's maybe why the smell didn't occur during warm weather.

Thanks for the help all!

 

[Twowaxhack]

Horns are for people who don’t want to correct the closet flange and want to make believe the horned wax will make up the difference. It doesn’t.

That’s my opinion and experience.

 

[Zanne]

I wonder if the problem only existing in winter was due to expansion/contraction issues? Wax may be colder and more brittle-- less malleable and adaptable when it is cold. That's my only guess on why it happens during winter. Glad you got it sorted out though.

 

[Mike-L]

Well, I celebrated a little early. The smell is back. I was with the plumber the day they swapped the ring and it was cold but mild and the smell was definitely there in the morning. The smell abated almost immediately after installing new ring (aired out the room for a couple hours), and I tested it again by running the shower downstairs for 15 minutes or so. No smell then but it was warmer, calm and sunny (40s). I returned a week later, to do some work, and no smell, but again it was in the 40s-50s and calm. I'm starting to think it's definitely a venting issue and possibly a combination of factors possibly also having to do with wind direction and pressure.

The expansion/contraction idea is one I thought about, but more along the lines of floor movement (there has been some settlement in the house) and maybe a shallow trap is losing its seal? Or a studor vent stuck open? (but wouldn't that be an issue on warm days too?)

Remember the vent terminates thru a side wall horizontally. A neighboring house with same floor plan vents the same way but tees so there are two openings. They don't have the same issue. Any other ideas? Thanks all!

 

[BlueSkyHigh]

I am surprised that, after all these years, science or magic has not come up with a better solution than the lowly wax seal. I guess the axiom "If it ain't broke don't fix it" applies here.

 

[dmmsr]

Worse in the winter? Put a 90 on that pipe that goes out and take it up a bit. Inspection or not, plumbing vents should not be terminated horizontally.

I am in agreement here. The vent is suppose to terminate a minimum 6 inches about the roof. During shower you are causing the sewer to heat up more with steam in the line. Methane gas is naturally light then air. The steam/moisture is mixing with it causing it to become heavier. Especially during winter it is not exhausting and dissipating out of the vent faster. If you were to run a cold shower I would almost bet, key word bet, that it would not happen. And if the wind is blowing when showering you are carrying it right back into your house. I had a customer who could smell sewer gas in their house periodically. More during windier times. Long story short I found that the one story side of their house had a rain gutter tied directly into their street side of a house trap. The winds going through the sewer and heavier winds outside caused it to blow into their house even with everything closed.

Have someone put a 90 on your vent and take it above the roof at least 6 inches keeping it 2 ft away and above any window.

 

[MicEd69]

I am surprised that, after all these years, science or magic has not come up with a better solution than the lowly wax seal. I guess the axiom "If it ain't broke don't fix it" applies here.

You mean like these?






The problem is, these just don't seem to work as well as the wax seals.

 

[BlueSkyHigh]

Yep, just like those and good to know that the original, possibly the product of bees, is still the best!

 

[Zanne]

Well, I celebrated a little early. The smell is back. I was with the plumber the day they swapped the ring and it was cold but mild and the smell was definitely there in the morning. The smell abated almost immediately after installing new ring (aired out the room for a couple hours), and I tested it again by running the shower downstairs for 15 minutes or so. No smell then but it was warmer, calm and sunny (40s). I returned a week later, to do some work, and no smell, but again it was in the 40s-50s and calm. I'm starting to think it's definitely a venting issue and possibly a combination of factors possibly also having to do with wind direction and pressure.

The expansion/contraction idea is one I thought about, but more along the lines of floor movement (there has been some settlement in the house) and maybe a shallow trap is losing its seal? Or a studor vent stuck open? (but wouldn't that be an issue on warm days too?)

Remember the vent terminates thru a side wall horizontally. A neighboring house with same floor plan vents the same way but tees so there are two openings. They don't have the same issue. Any other ideas? Thanks all!

Venting horizontally won't cut it. You need to put a 90 on it so it goes vertical and have it extend above the roofline. I'd go with min 18" above roof. I have one that goes up the outside of my house then has a 90 to go around the eaves (supposed to slope 1/4" per ft upward) and has another 90 going above the roof. It's a circuit vent so it comes out from under the house horizontally, then has the vertical 90, then another 90 to go horizontal, then a 3rd to go vertical again. It's ugly but better than nothing.