Back to back toilet drain issue

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drew53813

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Please review the following picture and advise. Thanks!
 

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Terry

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If you have room for two santees stacked, you would have room for a double wye.
Or I prefer to wye off the second toilet and vent both.

glynn_5.jpg
 
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drew53813

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Terry- please review the following picture so I can clarify your recommendation. Also, is there a min/max distance the vent for toilet number two needs to be from the soil stack? I am planning on using 4 inch ABS. Thanks.
 

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hj

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All of your three options are acceptable, as is a fourth one you did not mention. BUT, the vent on the last one HAS to connect back at least 42" above the floor, NOT down low as you show it.
 

drew53813

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HJ- this was a rough sketch. I plan on tying all my vents to the stack in the attic which will be a good 7 feet up. Mind sharing the 4th option? Thanks- Andrew
 

hj

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Back to back fixture fitting which is the "approved" one for that type of installation. A fifth one would be a sanitary cross which is NOT approved. Doing it with that additional vent is both time and money intensive so I would not do it, but you may have unlimited time and money.
 

Terry

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I won't install the double fixture fittings on back to back anymore. The water will skip over the cross with the new bowls, pushing water out of the opposite bowl. Flush one bowl three times and the opposite bowl has almost no water left.
They make a double wye fitting.

back_to_back.jpg

TOTO

back_to_back_kohler.jpg

Koher

Both mention "double wye"
Not double fixture fitting.

double-cross-copper.jpg


 
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TinaS

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Still an issue in 2019! If we would of known we would of tried to keep repairing old model. Nothing has solved our issue.

Plumber has tried vent, etc. and we still has a "geyser" in downstairs toilet when upstairs one is flashed and the water drains out. Uploaded pictures, the new vents, pipes are on right and can see what is new after jackhammering floor.

We cant afford to keep "fishing" for a solution. People should be told this can happen with any new toilet purchase if they have a back to back.

Solution that will work would be appreciated!
 

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