Sewer Gas At Washing Machine

Tanias55

First off, Iam totally embarassed to ask this question. I am a Texas master plumber and have been so for 30 yrs. I plumbed a new house around a year ago using Pvc sch 40 drain and vent lines. I plumbed the washer drain with 2"drain going directly into 3" drain some 5"away and 1 1/2" vent. The trap T's off the vertical vent close to the floor. We ran vent towards back of house about 20' making sure it had correct rise on it. Now when the homeowners
Run washer they get a sewer gas smell occasionally from washer drain. So I thought it must be vent, I cut vent going towards back of house and installed an Auto vent in attic. Which are considered legal in our area. This took care of problem for around 2 monthes, now They are getting it again. Any ideas would be greatly appreciated. Tanias55

Tom R

Sounds like a question for Plumguy, - - but I don't know if I'm understanding you right, - - do you mean the 'trap' is close to the floor??, - - shouldn't it be like 48" high??, - - or at the very least, - - 6" above washer 'rim' level to prevent siphoning??

Sounds like the trap and/or vent needs to be higher.

All right, - - I'll shut-up now (before I get in more trouble) and wait for Plumguy.

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K2

Any chance the floor drain trap is dry?

Tanias55

Sorry I didnt make it very clear, but the washer trap is about 6" above floor with a standpipe coming out of trap to washer box at 36" off floor. There is no floor drain in laundry room. Thanks, Tanias55

Tanias55

Something I just thought of. This house happens to be last house on this branch of sewer main. I wonder if sewer main could be building up enough gas to affect washer drain since its the most water going down sewer at a time. I might try installing 4" running trap on sewer coming out of house?

CEF

Could the vent pipe have been damaged in final construction, cut, drilled, broken within the wall? Is the smell REALLY sewer gas? Could this be water (sulfer ) -or some chemical ?

Tanias55

If the vent was damaged wouldnt it Smell all the time? Its definitly sewer gas. Thanks, Tanias55

Moscow

I have ran in to the same problem, I have no idea why it happend but, what fixed the problem is, I ran a reilf vent off the trap arm up and tied it back into the main vent stack and the problem was sloved. After your post on the main sewer gas I did some checking and what i found out was, if you have a lot of homes or buildings flowing into the city main and it is undersized you can get sewer gas to back up into the home, however if you have a trap seal then you should never get sewer gas to come out of a fixture. So long story short I am thinking that when the fixture dumps it dose it with such force that the trap seal is lost and with the reilf vent it know dosen't do that.
That is my 1 cent on this topic.
Good luck and let us know what you find out
Justin

Tom R

Hey Tania, - - I'm not a plumber, I'm a carpenter (who thinks he's a plumber too), - - so feel free to 'laugh' at my guesses (Plumguy always does ). But seriously, here's my 'best shot', - - the trap is far enough below the standpipe inlet that the 'fall' of the water is 'flushin' out the trap and leaving it empty. It just may not be happening every single time.

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Tom R

Just read back and realized Moscow's pretty much sayin' the same thing. Seems like the trap should only be about somewhere between 10 to 20 inches below the standpipe inlet.

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Moscow

Just to let you know the stand pipe in the Uniform Plumbing Code is mim of 18 inches not more the 30 inches. I would have to say for a carpenter the was a great guess :Thumbs: . I only think that it might be the dump to fast because in the newer clothes washer the dump cycal is much faster and lots more water then the older ones.
Chow for now
Justin

Tom R

Thanks for the good info, Moscow, - - I'll have to remember that.

Sounds like them damn washin' machines must be the 'opposite' of humans, - - what with that damn 'dump cycle' rate and all!!

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Moscow

I think tide to wash machines is like trubo lax to humans
One drink and your colin is clean

plumguy

I did not read the other posts ...so, maybe you have it solved. But, here the stand pipe out of the trap on a washer has to be between 18"-30". So if your'es is longer than that it might be siphoning the trap....considering the force(inertia) that a washer's pump creates.

plumguy

I'm a plumber..who thinks he's a carpenter!

plumguy

Oops! I knew I should of read the other posts! :Thumbs: :Thumbs:

Tom R

See, - - we'd make a good 'team', - - if nothin' else, - - we'd create a lot of work for each other!!

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Tanias55

Thanks Guys. I went back in wall and raised trap 5", That makes standpipe 24" seemed to do the trick. Thanks again. Tanias55