Bathtub P-trap level question

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Jim C

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Hi,
I'm currently replacing a bathtub and flooring in a bathroom but running into a slight dilemma.

I have a duplex where both bathrooms are side by side and the bathtub share a 2 inch main drain connected to a 2" x 1-1/2" x 1-1/2" x 1-1/2" double fixture sanitary tee.

I'm converting the bathtub from a center to a left drain. Modifying the sanitary tee is not an option as its connected to the other unit. I plan to run a 2" pipe along the length of the tub. (Image 3) with roughly a 1" slop along the 2" pipe from the left bathtub drain (1 -1/2") to the sanitary tee. (also 1 - 1/2")

The question now is I placed a p-trap close to the bathtub drain, but concerned that due to the height of the sanitary tee branch, and to get the slope, i raised the start of the 2" pipe to just under the drain entry level (Image 6). Would there be any issues with water draining or back flowing?

Thanks...
Jim

Image 1 - Before rerouting center bathtub drain
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Image 2- Before: 1 -1/2" 45 degree angle to center bathtub drain
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Image 3- After: Dry fitting pipes. Rerouted cold lines to accommodate new drain and p-trap
1_1024x768_zpsf3a38ecb.jpg


Image 4 - Close up of new drain and p-trap. Drain will be raised higher above sub-floor to meet bathtub and provide the 1" slope along the 2" pipe along the length of the tub.

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Image 5- Close of of the other end of the pipe. 2" to a reducer connecting to a 45 deg
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Image 6 - View from the end of the tub.
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Image 7 - This shows the concern where the end of the p-trap is not completely under the drain.
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hj

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Well, we have to start with photo #5. You CANNOT reduce the size of the pipe in the direction of the flow. In other words, you CAN connect a 1 1/2" pipe to a 2" one, but you CANNOT connect a 2" pipe to a 1 1/2" pipe. Therefore, your entire premise is incorrect and you have to start over, with the limitation that a 1 1/2" pipe can ONLY run 42" from the vent, which may be why they used a center outlet tub in the first place.
 

Jadnashua

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On a secondary note...because the socket on the fittings is tapered, it is nearly impossible to get the pipe bottomed into them when dry fitting...as a result, each fitting will likely add about 1/4-1/2" short in your run. The pipe only easily bottoms out when it is melted with the introduction of the cement.
 

Terry

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Since the drain is on the right side, why isn't a Right Hand tub being installed?
Like hj mentioned, the 1.5" on the right limit's you to 42" on the trap arm. To get 60", you would need the full 2" to the "top" of the pipe on the downhill side.
The vent is to "prevent" the trap from siphoning. If it siphons while draining, which it very likely will, you will have defeated the purpose of the proper vent, which was designed originally for a RH tub.

For the trap arm to vent itself, it can only rise 1/4" per foot in 42"

accord_wild_03.jpg
 
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Jim C

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Thanks all for the replies. I wasn't sure if I could go from a 2" pipe to 1 1/2" at the tee.

Here's the update from this morning. The second option as suggested by Terry was to look into a right hand tub. Initially I wasn't sure if there was enough space for the drain pipes or if there was enough space for shower handle fixtures or hot cold lines. The left end tub seems to be out of the question now.

Went to get another drain kit but the type with compression nut and gaskets. Attached p-trap and dry fitted sto another p-trap (horizontally) with some extra 1-1/2" pieces and a coupler.

The concern now is this setup provide little or no slope. Also I'm connecting a p-trap to another p-trap piece to u-turn the drain.

Does this setup look viable?

Thanks again for the comments and suggestions.
Jim
 
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Jadnashua

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You can't have that much change of direction. It looks like you could run the p-trap towards the connection instead of away from it.

There are tools that will let you ream out the pipe from the inside of a fitting so you can reuse it. One brand is called Ram Bit.
 

hj

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Why aren't you putting the "second P trap" directly on to the pipe where the coupling is and get rid of that hodpodge you are creating. You are making this a lot more difficult than necessary.
 

Jim C

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Ah. I'll look into the ram bit. Ideally I would connect the p-trap directly to the tee and avoid this uturn craziness. But I didn't know I could ream out the pipe from the inside of the tee.
 

Jim C

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Image 9 has a coupling cause I've already cut the drain past the 45 fitting.

I'm going to check if i can cut out the 45 fitting, if i can put the p-trap directly to the tee.

 
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hj

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There are a "lot of ways" you can connect the trap and NONE of them use that 180 degree turn, and maybe not a RamBit either. And, I would NEVER use a trap with "lock nut" under the floor.
 
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