Making an old cleanout into a new drain

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rosem637

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DTony maybe you can use a double WYE in place of that flush clean-out fitting.
I needed a 4" double wye and the big box stores did not carry it. I had to get it from a plumbing supply house.

A Wye is not the proper fitting for going from horizontal to vertical. Like cacher pointed out, a San-T is the way to go.
 

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Caduceus

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The above diagram from rosem637 does not apply to this situation as the kitchen will need to be independently vented and does not rely on 'stack venting'.
Do as cacher_chick recommended.
 

rosem637

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The above diagram from rosem637 does not apply to this situation as the kitchen will need to be independently vented and does not rely on 'stack venting'.
Do as cacher_chick recommended.


The diagram was used as an illustration to show that A Wye is not the proper fitting for going from horizontal to vertical. Not an actual stack with a combo and a san-t stacked on top each other
 

Caduceus

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The diagram was used as an illustration to show that A Wye is not the proper fitting for going from horizontal to vertical. Not an actual stack with a combo and a san-t stacked on top each other
Actually, a wye combo going from stack to branch is preferred if the horizontal branch is vented at the fixture. A sanitary tee acting in continuous waste and vent fashion is used for just that purpose...continuous waste and vent. If a wye combo on a vertical stack or double wye can be installed, then that is the preferred method.
 

Houptee

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I thought a wye can be used either horizontally or vertically for a change of direction?

Per Bert Polks guide:
Double combination y-1/8 bend.
This fitting is used to connect a
Horizontal drains to a vertical
stack .
 

Caduceus

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I thought a wye can be used either horizontally or vertically for a change of direction?

Per Bert Polks guide:
Double combination y-1/8 bend.
This fitting is used to connect a
Horizontal drains to a vertical
stack .

You CAN use a wye combo for a change of direction. What was not made clear by the image posted above was that the wye combo cannot be used as a continued drain and vent. The top of the image shows continuous waste and vent. The lower part of the image shows the wye combo being 'prohibited' if you are trying to vent a drain through the horizontal to vertical connection. If you use a wye combo, you must have a vent before it for the fixture trap.
This is what happens when information is given with no background on interpreting the information.
You will still find inspectors and code instructors who think that a wye combo is completely illegal for a horizontal to vertical drain connection, and a tee is the only acceptable method. Somehow this same info is leeching into code books and plumbing mythology is ending up in print as a fact.
Good plumbing practice relies on perpetuating good information and over the years the same misinformation is being repeated by lazy minded people because it's the easy way to reply and sound educated.
It's a shame that this is still happening and a skilled trade is dying.
 
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Houptee

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What about a toilet coming in horizontally with a double wye and other fixtures on the opposite side of wye with vent out the top?
Terry posted in a different thread that a double sani tee with newer toilets splashes across the double sani tee, and a double wye is better in that situation.
Since a toilet would not have a vent prior to the double wye is that technically prohibited?
 

Cacher_Chick

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Houptee, back to back fixtures should be on a double fixture fitting, not a double wye. The wye would require an additional vent or re-vent, regardless of the trap to vent distance.
 

Houptee

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Oh that screws me because I was planning to redo my upstairs bathroom that had been tied into a 4" vertical stack that continues up thru the roof.

It has a cast iron long turn combo wye laying flat on its side, with the toilet, lav, tub, and kitchen, all coming into the long turn end, then out the end of the combo a street 90 down into the stack, and off other end, another street 90 up the vent.

I was going to redo the cast iron in 4" PVC with the toilet flange in 4" dumping into one side of a 4" vertical double wye, 4" vent in center up to the roof, and then dump the lav, tub, kitchen into the other side of the wye but with a 3" bushing.

My thinking was the toilet would flow down a wye much better than a double sani tee without splashing across and get enough vent air since its 4".

With the other drains dumping from a 3" pipe into a 4" wye, with 4" vent in center, I thought that was plenty of air space, and the wye made all the drains at the same height so no wet venting is above the wye.

The kitchen line coming in will have a separate vent, but the bathroom lav and tub is not vented due to its so close to the stack and the wye I was going to drop into.

So I guess that would not be code compliant using a vertical wye with vent in center, but a double sani tee would be?
 

rosem637

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You CAN use a wye combo for a change of direction.

Yes, but the change of direction has to be a vertical drain to a horizontal drain or a horizontal drain to a horizontal drain.

Using a Wye-combo to go from horizontal to vertical in a no.
 
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rosem637

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I thought a wye can be used either horizontally or vertically for a change of direction?

Per Bert Polks guide: Double combination y-1/8 bend. This fitting is used to connect a Horizontal drains to a vertical stack .

double fixture cross
 

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Caduceus

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Yes, but the change of direction has to be a vertical drain to a horizontal drain or a horizontal drain to a horizontal drain.

Using a Wye-combo to go from horizontal to vertical in a no.

I don't think that you get it yet. A double wye combo or a wye combo is allowable if the fixture is vented before the combo as cacher_chick also pointed out. It should also be mentioned that the double fixture cross shown next to the double santee has a vent connection in the center of the fitting that sits below the top of the connecting horizontal pipes. This is not acceptable when determining hydraulic grade on trap to vent distances. It may slip past an inspector or two, but it because of the elevated flow line of the fitting, it now takes on the characteristic of a twin wye combo.
If your going to preach codes you should also mention the need for a cleanout on fixtures connected with a double tee on the vertical portion of the pipe. Using a double wye combo doesn't require a clean out because there is no risk of jumping the fitting and entering the nearby fixture.
When you did your drawings in plumbing school, rosem637, and during your journeyman or masters testing, these details were required so that plans and permits could be filed and isometric drawing could be properly interpreted.
 

rosem637

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It should also be mentioned that the double fixture cross has a vent connection in the center of the fitting that sits below the top of the connecting horizontal pipes. This is not acceptable when determining hydraulic grade on trap to vent distances. It may slip past an inspector or two, but it because of the elevated flow line of the fitting, it now takes on the characteristic of a twin wye combo.

I am not a plumber. The info you quoted was interesting. I have never notice that the tap on top the DFC does sit below the the top of the horizontal lines that would connect to it.

I think that Double Fixture Cross, Double San-T's and Double Wye Combos are the most difficult to understand when and where to use.
 

Caduceus

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I like the way that you pointed that out. For the transition to fill with water as depicted in the illustration, the stack would have to be filled with water. That is why stack venting of water closets with a wye combo is preferred and on our journeyman and master's tests to draw out a plan without the 45 off of the stack is a point reduction and implies a tee is in use.
some codes would refer to that as s-trapping a toilet, but as stated in the past, toilets do not operate on the same principles as a standard fixture trap.
 

Houptee

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What if you had a toilet go direct from the flange with a 45, then about 2' of pipe, then directly into the wye hub, so no horizontal arm at all and no 1/8 bend at the wye?
 

Caduceus

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What if you had a toilet go direct from the flange with a 45, then about 2' of pipe, then directly into the wye hub, so no horizontal arm at all and no 1/8 bend at the wye?

Then you would have a stack vented water closet. Congratulations!:D
 

Caduceus

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But the previous posts said you would need a vent or a revent before the wye.
Is that only for fixtures other than a water closet?

Yes. Toilets are different than other fixtures, but there are a number of other codes that apply to many possible installations of toilet drains and vents that cannot be thoroughly covered on a forum. That's why we have plumbing schools.
 
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