Kitchen sink drain


  #1  
Old 03-10-21, 06:40 PM
J
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Kitchen sink drain

Hello,

I have an issue with a new sink Im installing is deeper than the old one. Its a single bowl with disposal and is under mount which makes it lower even more. The existing drain is horizontal and runs about 4 feet over and ties into the main stack in the wall. If a reverse J bend trap doesnt work for me Im looking for alternatives ? Maybe run drain down into basement and tie into the same stack but at a lower point ? How would I do this ? Ive see a saddle t conversion with a gasket that clamps onto the cast iron pipe not sure if this would work ? Attaching pics as reference. Thanks for any advice yall have.



Stack is all the way to the left just inside wall. The bathroom sink on the other side of this wall also ties in here.

This is in basement just below where kitchen and bath sink tie in.


Toilet going to stack

Tub/shower tie into same line as toilet

 
  #2  
Old 03-11-21, 10:49 AM
Z
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What are those other PVC pipes?

You can cut into the CI stack, add a wye, and drain into that. You'll need a vent too, which might be able to be an AAV if your locale allows it. But cutting the stack will be a project. You'll need to support it, cut about 12-16" out, and replace with a pair of no-hub couplings and PVC. Doable, but a decent project.

(I thought the disposer was attached at first and couldn't quite figure out why it looked so different... finally clued in that it's just sitting in the cabinet!)
 
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Old 03-13-21, 07:29 PM
J
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The PVC you see is part of my central vac system ( Oh how I wish that was DWV)

So if I was to cut in a WYE down there where would the vent tie in ? I can't do an AAV as they are not allowed here unfortunately.
 
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Old 03-14-21, 07:52 AM
Z
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So if I was to cut in a WYE down there where would the vent tie in ?
You'll have to run a pipe up the wall and out the roof. From the kitchen sink, it's always a bit of a challenge as you probably have to go around a window. Last resort, you can poke outside and run the pipe up the wall on the outside of the house, though that's sometimes an eyesore.

Unfortunately, without an AAV, there's no way to vent 'from the bottom'.
 
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Old 03-14-21, 04:53 PM
J
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Ok thanks. We are deleting the disposal for now.. not thrilled about this but in the future we can get to all this through the shower wall when we redo the bathroom again..
Out of curiosity how far can you run that pipe horizontal before it hits the new vent to go up and down ? And also could I cut into the existing CI stack above the height of the kitchen sink and re vent ?
 
  #6  
Old 03-14-21, 05:14 PM
Z
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how far can you run that pipe horizontal before it hits the new vent to go up
For a 1.5" drain pipe, the pipe can run up to 6' horizontally from the trap to the vent. The vent needs to be branch off before the drain goes vertically.

could I cut into the existing CI stack above the height of the kitchen sink and re vent
Yes, if there are no fixtures above that point in the stack. If you have a 2nd floor bath or something draining into the stack, it can't be used as a wet vent. (It may have been allowed when the house was built, but no longer). It would need to be at least 6" above the flood rim of the sink.
 
 

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