P-Trap Under Floor

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jammy

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Hello:

My son just moved into a new house and has a botch-job of a disposal drain that we need to fix. See pics.

The problem is that the drain line under the kitchen sink is 3-4" above the disposal outlet. We cannot open up the wall and tap into the existing drain pipe lower down because the drain runs horizontally (to the right of the sink) behind several cabinets until it joins with the vertical drain/vent stack. The stack is to the right because, as you can see, there is a large window behind the sink. I am 100% sure that there is nothing else draining into this drain from upstairs; there are no bathrooms etc. above the kitchen and the vent pipe goes straight up to a roof vent.

I would like to run the disposal drain straight down through the bottom of the cabinet and floor into the basement and put the p-trap in the ceiling of the basement. I could then tap into the drain/vent that is right below the kitchen in the basement.



Thanks for your constructive inputs!
 
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Terry

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You could come up from below, and a p-trap and above the santee for that, an AAV.

Also, mixing ABS and PVC is wrong. With PVC pipes, you should have had PVC fittings.

seaton_sink_1.jpg


seaton_sink_3.jpg
 

jammy

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You could come up from below, and a p-trap and above the santee for that, an AAV.

Also, mixing ABS and PVC is wrong. With PVC pipes, you should have had PVC fittings.

seaton_sink_1.jpg


seaton_sink_3.jpg
Terry: I don't get this reply. Was it meant for another thread? I have no mixed ABS and PVC.
 

jammy

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Pictures showed PVC pipes with ABS fittings.
Ah, yes! Sorry. Was just looking under the sink. Yes, I see that. That was all existing mess that I will have to clean up eventually. I may just cut those elbows out when I do the disposal drain.

BTW, The drain I am tapping into in the basement continues up as a vent, so I don't need the AAV, right? Here's what I would be doing.
 
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jammy

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You need the vent.
If the tail piece is too long, it also siphons the trap.

Terry: I assume that by tailpiece you mean the vertical pipe that will be going from the disposal drain down to the p-trap in the basement. Yes, that could be 3-4 feet in length. The p-trap itself will only be inches from the drain/vent. So, AAV still required, huh?
 

Terry

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Yes, it's all about keeping water in the trap. Sometimes people mistake the cool sucking sound as really good, when it's pulling water from the trap and allowing the stink into the home.
 

Jadnashua

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Most codes require the trap to be above the floor...i.e., not beneath the sink it serves. There is a limit on the height of the downpipe.

Not to throw a wrench in the works, but MA is one of the (few) states that outright prohibits a homeowner from doing plumbing work on his own property unless he is a licensed plumber. I'm not saying that I agree with that, but it is the state law. Proceed carefully. You're not alone, but that doesn't mean you may not have issues.
 

jammy

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Yes, it's all about keeping water in the trap. Sometimes people mistake the cool sucking sound as really good, when it's pulling water from the trap and allowing the stink into the home.

Thanks, Terry. You have saved me (and thousands of other would-be plumbers) a lot of time and trouble. And helped us do things right in the process.
 

jammy

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Most codes require the trap to be above the floor...i.e., not beneath the sink it serves. There is a limit on the height of the downpipe.

Not to throw a wrench in the works, but MA is one of the (few) states that outright prohibits a homeowner from doing plumbing work on his own property unless he is a licensed plumber. I'm not saying that I agree with that, but it is the state law. Proceed carefully. You're not alone, but that doesn't mean you may not have issues.


Thanks, jadnashua: I knew about the MA rule. My location shows MA, but my son's home is in MD. I love these laws that say that only licensed xyz's can do the work. I can't count the amount of time I have spent fixing incorrect work done by "licensed" tradespeople that was supposedly inspected by "professional" Inspectors. To add insult to injury, when I post pictures on the forum, I get yelled at by other pros (not Terry) as if I was responsible for the shoddy work!! OK, enough ranting. Sorry.
 
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