Plumber installed double sanitary tee in back to back install of eco drakes

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natalie559

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The plumber is coming over on Wed am to look at the cut beam and address my concerns on the type of fitting used. If he tells me the fitting is to code and that he installs them without issue would you still have him replace it to a wye fitting based on your experience dealing and reading of these types of issues? Plumber also said that he didn't use a sanitary t but a cross type t, I think it's referred to a double fixture fitting- I dont remember exactly what he called it, but from looking my pic it's not the best type right?
 
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Terry

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From the Kohler instructions.

back_to_back_kohler.jpg


A double wye fitting on the left is okay
A double fixture fitting is marginal, it will still lose water in the bowls.
A double Santee on the right doesn't not work well at all.

back_to_back.jpg


As water jumps from one arm to the other, it displaces air. It pushes air up into the opposing bowl. When air comes into the bowl, it raises the water level, and when that happens, the water then slops over the dam, the highest point of the trapway, and down the drain.

I am waiting for the rest of the plumbers to figure out this simple problem.
I'm waiting for the plumbing code to be re-written to solve this very simple issue. Both Kohler and TOTO are aware of this, I'm aware of it, and bit by bit, plumbing inspectors are being asked about it.

Cut out the double santee.
Replace with a double wye fitting. You don't want any water going up the other arm.
A double fixture fitting won't work either. It's not as bad as the double santee, but it's also not the solution. It also allow "water skip", which pushes air into the other bowl, thus slopping water over the trapway dam, and lose of bowl fill.
 

WJcandee

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Terry, for what it's worth, the newest Toto instructions are even more definitive than the ones you quoted:

"IMPORTANT!
Due to the powerful performance of our Cyclone, G-Max, E-Max and Power Gravity
flushing systems, they are not specified for back-to-back installations. The only
means of installing these toilets in a back-to-back situation is when the toilet drain
connections incorporate a WYE fitting. Please contact your builder or contractor prior
to this installation.
Double Combination WYE / 1/8 Bend
YES
Double Sanitary Tee / Sanitary Cross
NO"
 

natalie559

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Thank you all!!

Plumber came by this am and looked at everything. His opinion was that the fitting was just fine and wouldn't cause me issues, said the water in that pipe wasn't anything to worry about. I disagree based on what I've read and said that given this great opportunity to do things better with the bathroom being opened up that I want the fitting that the manual states is the correct one. He said he would replace it to what I want and given the space the new fixture would need to be cut in lower (which if used in the first place would have avoided the cutting of the joist). Coming in lower will avoid any pipe in the joist space and a new 2x8 beam with be attached next to the one that was cut.

What confused me and I didn't have the knowledge to reply very much was that he said the double combination fixture wouldn't be to code. I don't understand how that would be. I looked up Fla code and this is what it states (see chart below),

"706.3 Installation of fittings.
Fittings shall be installed to guide sewage and waste in the
direction of flow. Change in direction shall be made by
fittings installed in accordance with
Table 706.3. Change in direction by combination fittings, side
inlets or increasers shall be installed in accordance with Table
706.3 based on the pattern of flow created by the fitting.
Double sanitary tee patterns shall not receive the discharge of
back-to-back water closets and fixtures or appliances with
pumping action discharge.

Exception:
Back-to-back water closet connections to double sanitary tees
shall be permitted where the horizontal developed length
between the outlet of the water closet and
the connection to the double sanitary tee pattern is 18 inches
(457 mm) or greater."

photo.jpg

Also I'm confused about a double fixture fitting vs double wye fitting- what is the difference and how do I make sure they use the right one?
 

Jadnashua

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A double fixture fitting is more rounded, the double wye fitting has obvious straight 'Y' inlets. After looking at them, it should become obvious why the double wye fitting can't allow skip over.
 

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WJcandee

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When you look at Jim's pictures, the one on the right is a double-wye, to which one adds a 1/8 (45-degree) bend on each side so the horizontal pipe will go into it. One can also purchase the "double-combination Y-1/8 bend" as a single unit. As Jim says, you can see how the Y portion of that fitting makes skipover very unlikely.

One thing your plumber may be saying is that it is typically prohibited to use a combo Y-1/8 to connect a trap arm to a stack, because the weir of the p-trap will be above the top of the opening of the fitting that connects it to the vent. And the connection from the toilet flange to the stack is considered to be a trap arm. Local code may be written to say that only a double-fixture fitting is appropriate in that circumstance. However, this logically shouldn't be an issue because the toilet has its own built-in p-trap; there is no "weir" on that portion of the trap arm. That's the technical explanation, I think... Whether a local inspector would consider it to be acceptable is another issue...
 

natalie559

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Thanks for the info and esp the pictures Jim- very helpful! The plumbers came by yest and I think we're all sorted out now- take a look

photo2.jpg

image2.jpg
 
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