Kitchen sink back flow

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  #1  
Old 03-10-14, 01:57 PM
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Kitchen sink back flow

I am having a kitchen sink back flow problem. Any suggestions would be greatly appreciated.

My daughter’s kitchen is right above mine, if she pulls the sink plug with a full sink of water, some of it back flows into my kitchen sink, along with the smell of about 100 dead rats!

I have run a snake and checked to the best of my ability, that the lines are clear and they seem to be in good shape, I can see down the cleanout in parts of line and all looks fine. I have good drainage from the first floor, as does she on the second floor, albeit that she causes the back up in my sink.

Her drain has a straight vertical drop of about 14 feet in 2 inch galvanized pipe that also goes up through the skylight housing to act as a vent. Downwards, it hits a 45 degree and is off for another 1.5 feet where a Y takes into a horizontal run of about 10 feet to the stack. The other end of the Y is the clean out.

Is this caused by the pipe not being able to process the rush at the bottom most elbow, venting not being able to keep up, or both?

If I were to remove the old pipe and replace it with ABS, and install a P trap at the half way mark, would that slow the 14 foot rush enough to allow her sink to drain with stink bombing my kitchen?
 
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Old 03-10-14, 04:59 PM
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Hello...
1. You have a clogg in that kitchen sink line.
2.Your sink connection should be a Y connected to the stack.
3. You sink is wet vented and needs its own vent per U.S. code
4. None of the bathrooms are vented to code if your drawing is correct. ( another wet vent thats not to code)

I am surprised no one is sick in the home from sewer gas. ( Or possible death can occur too.) I am sure most of the traps are siphoning out when other fixtures are used.
 
  #3  
Old 03-10-14, 06:59 PM
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Hi Mike,

Thank you, you are confirming what I feared.
The house is about 70 years old, most the drain pipes are original. I changed the drinking water lines when I bought a few months back, but now it is time to look at the waste water system.
What would an ideal system look like?

The drains run down a service chamber, 2.5' by 5', so I have full access.
Question is, how and what should I change to see the greatest gain?

Thanks!
 
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Old 03-11-14, 06:31 PM
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Any suggestions on how to improve the venting of these lines?
Would adding an AAV be a decent short term help until I can replace the lines?
 
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Old 03-11-14, 07:45 PM
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Hope this makes sense...

Name:  rough.jpg
Views: 3963
Size:  19.1 KB
 
  #6  
Old 03-12-14, 06:17 AM
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Thank you Mike!

The kitchen wall backs on a cement wall, there is less than 1" of space for the interior wall. Would it be ok to run the new dry vent line horizontally for about 4.5 feet and then run a new vertical vent up through the roof in the "service chamber"?

I could do the same for the lower bathroom too, it would be a little than a 4 foot run to join the new vent.

The upper bathroom sink may be tougher, I just did a full reno and there is a brand new ceramic tile wall.
There is room to add an AAV to the upper bathroom sink.
 
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Old 03-12-14, 10:03 AM
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Yes your plan looks OK... ......
 
  #8  
Old 03-12-14, 06:52 PM
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Thank you very much Mike.
I will start this weekend by cutting out just under 1/2 of the galvanized vertical 2 inch run and add a clean out.
Then in sections replace the entire galvanized line and then add the second vent line. Hopefully I can have it all done in a few weekends.
 
  #9  
Old 03-16-14, 07:10 AM
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Mike,

Just a quick follow up.
When you said I had a clog, I was not sure after checking in the cleanout, the line looked good inside. But the cleanout only shows the horizontal line in the basement. Thinking, he must be right, it makes sense, I cut out about 5 feet of the galvanized steel vertical line and installed a cleanout above where the lower sink joins the drain line. I was not expecting what I found.

It is as if the water from the upper sink hits the joint where the lower enters the line, causing "turbulence" in the flow and and for a few feet around that spot, there is so much build up on the inside of the pipe, the drain area is about a 1/2 inch, not 2 inches!

I have cut out and replaced about 1/3 of the line. Next weekend I will do another 1/3 or so and finish it off the weekend after.

Thanks for the help!


(the top picture is after an aggressive run with a drain auger, I just cut the entire section out after the drain auger only cleared a fraction of the wall build up).
 
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Old 03-16-14, 10:41 AM
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Can I leave the steel strapping directly on the ABS, or should there be a rubber cushion between the two materials?

I looked through the archives and could not find a thread that outline what best practice would be.
 
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Old 03-16-14, 10:47 AM
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I use the coated hangers....

DWVPVC64-192 - Carpenter & Paterson DWVPVC64-192 - 4" DWV Hanger (PVC Coated)

Looks very good and glad you found the proper mission coupling...
 
  #12  
Old 03-16-14, 03:06 PM
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drain

I figured that you must have had a clog as well as I read the beginning post that you made. It is a good thing that Mike ran across it and told you about it. He had some great detailed drawings of the drain route as well as with the vents.

Yeah, the pipe looks so thick with old stuff that it would be just like having a pipe that is too small for your drain, because that would be like having it try to drain on a pipe that is smaller because it was so clogged up.
 
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