Smelly sink/vent

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pedge

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I have a little sink with very tight clearances and several months after the completed house I noticed a foul smell and traced it to a small sink in a small bathroom. The plumber suggested I put a p trap in the wall in addition to the bottle trap on the sink. I have isolated the smell to this drain. When a plug is placed in the drain without the sink attached the smell stops. While I was placing the p trap in the wall I noticed an open drain pipe that had been drywalled over. I cut the drain line to the sink in question and added the p trap and attached it to the found drain line. I also plugged up the prior stub line that went to the drain. I am attaching photos. I can leave the drain pipe open now and for most of the time there is no smell however there are times when the smell comes. I have installed the sink back on the drain but due to the clearance issues, the tailpiece touches the bottle trap and has a slight angle to the drain in the wall. I have tightened up the 1.25 to 1.5 pvc washer as tight as it can go. I have taken apart and put back the bottle trap several times and everything still seems tight but alas the smell returns. What do I need to do to fix this?
 

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Sylvan

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GET A REAL PLUMBER as anyone suggesting a double trap cannot be trusted
 

pedge

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At this point since there is a trap in the wall, the bottle trap should be removed?
 

Sylvan

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The only time I ever concealed a trap was for the following

1- Shower

2- Bathtub

3- Floor drain

4- Floor type urinal that also was used as a floor drain

All the others were accessible or having access to their clean out
 

pedge

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A sink uses a single p-trap that is vented.
An unvented p-trap will siphon dry. Do you have a vent on that system?
Yes, There is a vent just to the left side of the stud in the picture, it is just outside the edge of the frame.
 

pedge

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Well, I guess a trap door could be placed over this trap. Its behind a cabinet so it wouldn't be seen unless the drawers are removed.
 

pedge

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The vertical drop is very close to 24 inches. should I be worried about water flowing through the trap and not sticking in it?
 

wwhitney

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Basically, the advice to put a trap in the wall was wrong. The trap in the wall should be removed, and provisions for a trap outside the wall should be restored.

As you have the wall open, temporarily cap the trap arm, e.g. with a rubber cap. There should be no sewer smell; if there is, there is some other problem with the DWV piping in the wall. If there isn't, but the sewer smell returns when you reinstall the sink with barrel trap, then there is some problem with the barrel trap or its downstream connections.

Cheers, Wayne
 

pedge

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This is what I experienced Wayne. There is a problem with the bottle trap or its connections however there is no room to put anything else. A conventional trap will not fit under this sink. The sink is only 8 x 19 and there is a cabinet below it. I did take apart the bottle trap, put water in it and blew from the drain side. The water did flow out up through the top. There doesn't seem to be a problem with it. Also, the connections are near impossible to tighten behind the bottle trap.
 

wwhitney

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Could you box out part of the stud bay to provide an additional 3.5" of depth in the location where the trap goes, to allow a conventional p-trap? Otherwise, you have to get the bottle trap to work properly, or get a new sink/cabinet that will accomodate a proper p-trap.

Cheers, Wayne
 

pedge

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unfortunately, the conventional trap and changing the cabinet are the last resort. This would require major work and major money.
 
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pedge

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I have noticed at the same time the sink gasses a smell by the washer on the other side of the house.
 

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Is it possible that a stopped up studor vent in another part of the house could cause the ptrap to let off gas and the smell?
This would possibly also explain the smell at the washer dryer combo?
 

Reach4

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Is it possible that a stopped up studor vent in another part of the house could cause the ptrap to let off gas and the smell?
I can't see how that explanation would work.

To see if the smell is from the standpipe or the machine, consider making a temporary separation with a cheap plastic dropcloth. See which side of the plastic has the smell.

For your musty-smelling front loader, try leaving the door open to let things dry out. Also consider a washer cleaning cycle. See if your instructions tell you how to do that cycle. Include chlorine bleach.

Try this search in a search engine: smelly washer dryer
 

pedge

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My current understanding is this. The smell comes from the drain (sink 1) even when no sink or connectors are added. This leads me to believe that there is a siphoning issue. If this is the case, a vent exists within 38 horizontal inches and 16 vertical inches from the drain pipe. The crown weir is slightly above the vent connection but not above the top of the vent inlet Y. It is 8 inches from the vent, it satisfies the minimum distance from trap to vent. I put 2 buckets of water down the vent from the roof and it seemed to flow clearly down the (vent/drain).
A few of the reasons why a drain is siphoning are:
Wind oscillation: No observation of movement in the toilet when heavy winds.
Siphoning S trap: The 8 inch distance is greater than the minimum distance and there is a vent.
Capillary Attraction: Uncertain because I can't investigate this.
Evaporation: The smell occurs even after water has be run down the drain so this can't be the issue.
Momentum: The vertical height is only 16 inches <24 inches should not be a problem.
I am attaching a new better photo and a dimensioned diagram. The green lines represent the change from original addition of trap.
Does anyone have any insight?
IMG_0912.JPG
IMG_2504.JPG
 

Reach4

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I don't understand the significance of green in your sketch.

Try running the water in the sink at a trickle rate for a minute. That should fill the trap. If the smell still occurs, I would think the smell is just stuff in the lavatory drain and overflow passages. I would try closing the stopper. Fill the bowel with water. Put 1/4 cup of bleach into the bowl. Run water at a trickle for a half hour. The hope would be to kill some of the stuff growing in the sink passages. Then drain the bowl..

If you are on city sewer, I would increase the killing strength of the water in the bowl by using more bleach and adding a limit amount of vinegar.

I am not a plumber.
 

Reach4

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Never mix bleach and and acid (e.g. vinegar), it will generate chlorine gas.
All absolute statements are wrong. ;)

OK... yours is wrong, in that chlorine gas is not produced if you only use enough vinegar to bring the pH down below 5.
 
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