Kitchen Sink Trap in Basement

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DTrain

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Hello Folks,

I've lurked here tons! I've found about everything I've needed for about 2 years. And now I just can't seem to find what I'm looking for, so I'm stepping from the shadows to ask a question. Here goes:

Kitchen is getting redone. My current sink drain has a 10" drop distance to a 90degree horizontal run. That run is parallel to the back wall the sink is mounted to. It runs about 16" to a 90degree bend down into the basement where the trap is located. The horizontal run from the trap runs about 8' to the waste stack. All of these pipes are in a common plane all the way to the stack. First there is a problem with the vertical distance from the drain to the trap. more than 24" and there are two 90 bends in between.

Not sure why it was plumbed this way. The horizontal run under the sink before the downward turn to the trap in the basement seems to only solve that the pipe would've run thru the wall that separates the garage from the basement. Doesn't seem like a big deal?

Any way, if I were to put the trap under the sink then turn down immediately after the trap, would that create like an "s" trap, which from what I understand, isn't a great thing. Or is it ok to go straight down after the trap?

Thanks in advance!
 

Jadnashua

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The trap must be vented before you turn it down. And, that vent must occur before the trap arm has traveled too far (that depends on the pipe diameter - basically the bigger the pipe, the further away the vent can be - there must be a path for air, or things can siphon, and with 1/4" per foot, that limits the distance).

If where you live, they allow an AAV, that can work as the vent. You'd run the AAV up on the trap arm as high as you can conveniently get it and still replace it when it fails, and then you can go down at any distance or angle you want. IOW, you MUST vent before your pipe turns down after the trap. What your local inspector will allow, varies.
 

Asktom

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Depending on what "Kitchen is getting redone" means, if at all possible put a 1 1/2" vent through the roof. As stated, you can't drop down between the trap and the vent. AAVs are mechanical so they will fail eventually fail and only protect against negative pressure. A vent through the roof protects against both positive and negative and operates by gravity (atmospheric pressure). Gravity is more reliable than stuff from the hardware store.

Exactly how you might do this would require more information. Pictures would help.
 

DTrain

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Ok. Redone means new cabinetry, floors and wall paneling. I have a two story. I have a single vent, and everything in the house is "wet vented?". The kitchen is currently not at all vented then since the drain goes down, over , down, trap and over 8' to the stack. Everything drains fine currently and I never get icky smells. Two sinks and a new bosch dishwasher all use that line! Anyway to vent I'd need to run into the exterior wall beside the kitchen window (as the sink is under that window) and up into my bedroom wall, into the attic space and thru the roof. Sound right? That AAV sounds pretty easy. But as Asktom says, better to take the more reliable route. Any way to vent and out the wall to outside before hitting second floor.

Charging camera now. Will post a photo to help clear things up.

Thanks for the replies so far!
 

DTrain

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Here is a picture of under the sink. That pipe travels down thru the floor to the trap. The trap is below the joists in the basement. Keeps heading to the left in a straight line to the stack.

DSC03227.jpg
 

DTrain

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I was hoping for some advice to remedy this....

This place was built in 1957. It had one owner before me and I've been here 3 years. Far as I can tell everything looks untouched since original construction. Including the 1961 Kelvinator range, 1961 KitchenAid Dishwasher and 1965 GE wall oven! I would imagine that at the time it was built it was installed by a professional.
 

hj

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quote; I was hoping for some advice to remedy this....

Then you were hoping for a miracle, because there is no economical cure for it. The trap is too far below the sink, and apparently too far horizontally also, plus the distance from the trap to the drain connection, from your description, is also too long. Having a "single vent" does NOT mean everything is "wet vented", and would usually mean that things are NOT vented at all. It was done that way because the installer did not know how to do it correctly. IF it was installed by a "professional" then the next question would be "a professional WHAT", because he was NOT a plumber.
 

Jadnashua

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Not living in MA, I haven't researched, so I do not know when the requirement for all plumbing to be done by a licensed plumber came into existence...probably a long time ago. Some inspectors would sign off on anything...doesn't mean it was right.

You only 'need' one roof penetration for a vent covering the whole house, but it may be more expedient, depending on the layout, to use more. The size of the vent is determined by what is being vented, and the lines can be combined before they exit the roof, if done properly. Often, where it frequently gets below freezing, today's code requires the roof penetration to be bigger...that helps to prevent the moist air from condensing/freezing, and then plugging the vent. That doesn't mean the entire vent must be that size, that is determined by what is being vented.

FWIW, most things will drain perfectly fine without a vent...but in the process, without venting, could result in sucking other traps dry in the system in the process.
 
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Gib

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Kitchen trap in basement needs to be removed and reconnect section of piping in the basement using 45 degree offset or 90 degree long sweep when going from vertical to horizontal or horizontal to horizontal. In the cabinet vertical pipe coming from basement, instead of a 1/4 bend(90) put in a tee. From the branch of the tee use a double wye. Run each branch over to each bowl of the sink if you have a double bowl sink. Put a clean out in the run of double wye fitting. No offsets coming out of traps. Set your traps so you come straight down from sink and food disposal. Back to the tee, the run of the tee(top of tee) is your vent. Pipe out through roof. 12" below roof increase size of pipe before you penetrate roof. Where I'm from mechanical vents are illegal so I can't speak on that.
 
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