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 intermittent sewer gas smell & running trap suggestion
Author: swearingen (PA)

My problem is similar to the Methane Gas post, in that we both have the nasty smell, but different, so will post separately. I've been in the house for 1.5 years. The house is 63 years old and hooked to public sewer (in Pennsylvania). On a recurrent and intermittent, random basis, the house is overcome with sewer gas smell. I've had the borough sewer department here -- nothing found with the sewer main. Had the fire department here to check methane levels -- OK on the 2 occasions they were here, but no promises as to methane levels on the dozens of other times. I do not have central AC. Smell does not occur in any pattern related to plumbing fixture usage. This is a small house with all fixtures and drains used regularly, so not "drying" out. I had the vent pipe checked for blockage (snaked), with none found. The vent pipe was extended with an elbow that brought it above the roof line because it originally was just a 2" pipe extending a short distance straight out of the 2nd floor wall outside the upstairs bathroom. One plumber came up with one remedy , but the "remedy" did not seem to me to have anything to do with the problem (e.g. removed my garbage disposal) and the problem continues, without the garbage disposal. Another plumber said that the entire plumbing system would need to be re-vented. I just had a 3rd plumber come and say that he'd first correct what appears to be a "hokey" drain hose done by previous homeowner on the dishwasher. If that didn't solve it, he suggested a "running trap" outside, off of my lateral sewer line that runs to the public sewer main. He said I probably have a crack in a cast iron drain pipe behind the wall. He said the "running trap" will solve the sewer gas odor, although it would not solve the cracked pipe. And, he said that the cracked pipe might not ever leak, but that short of tearing out walls, he's suggest the "running trap". None of the plumbers I've contacted can or will do a "smoke test" and everyone just seems to be guessing. Would the best route be just to add a "running trap"? Plumbing forums seem to suggest that they are illegal and unwise, but I'm not sure if we're talking about the same things.

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 Re: intermittent sewer gas smell & running trap suggestion
Author: packy (MA)

yikes, the plumbing for your entire house was vented by one 2" pipe sticking out the side?
makes me wonder about the rest of the venting. do you have any "glug,glug,glug" when some fixture/s drain?
it could very well be a venting problem.
i have seen some strange things happen with venting in houses.
sometimes everything works fine until the wind is blowing in a certain direction.
sometimes everything works fine until the local sewer pumping station (located at a low point in the city) needs to turn on.
sometimes you can go on a roof, hold a lit cigarette over the vent pipe and the smoke is pulled in. you can go to another house do the same thing and the smoke will not be pulled in.
so, while i don't think the garbage disposer had anything to do with your problem, either of the two other plumbers could be right. maybe both of them are right ????

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 Re: intermittent sewer gas smell & running trap suggestion
Author: swearingen (PA)

At the beginning of this saga, the upstairs bathroom sink glugged whenever the tub or the sink was drained (but not when the toilet was flushed). I had pipes that sprung a huge leak under that bathtub, into the kitchen below. (Interestingly, this leak happened the day after the plumber was here investigating the "glug" and said he could not find anything.) After he came back and went in through the kitchen ceiling, the plumber said that the pipes under the tub were corroded and clogged from corrosion. He replaced a section of pipe(s) under the tub. After that, the glugging is "almost" completely gone. Every once in a while, it glugs a little bit when draining the bathtub.

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 Re: intermittent sewer gas smell & running trap suggestion
Author: LemonPlumber (FL)

Well seems all have been at or near the kitchen?Is the kitchen in the center of all the plumbing fixtures?I would pull and telescope all the sewer and or building clean outs to out side.Did the methane reading zero out?Running trap, no!fix the problem or remove it do not add to it.

Edited 1 times.

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 Re: intermittent sewer gas smell & running trap suggestion
Author: SMSPlumbing (PA)

I would not install a running trap. It is also known as a building trap. These are now illegal according to the International Plumbing Code, which is what most of PA uses as their mainstream code.

Does the smell seem stronger in certain areas, or does it seem to be the same through out the house? I would suggest finding a company that does smoke tests and have them come out and do a test.

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 Re: intermittent sewer gas smell & running trap suggestion
Author: ThePremierPlumber (NC)

Find a plumber that will do a smoke test. Best option.

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 Re: intermittent sewer gas smell & running trap suggestion
Author: dlh (TX)

do you have a gas log fireplace? could very well be a downdraft if so

other than that you need to get a leak locating specialist which should have the ability to do a smoke test

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 Re: intermittent sewer gas smell & running trap suggestion
Author: hj (AZ)

Running traps are sometimes illegal, but ALWAYS unwise, and until you know exactly where there problem is it may not be the cure. The dishwasher hose and the disposer would be very unlikely causes of the odor.

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