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Coupe
totally baffled

a friend of mine has two bathrooms upstairs back to back. when he flushes one the other starts to drain down. this works both ways. we snaked the vent pipe but the problem still persists. is there a way for, say like a plastic toy or small ball to hang up in the double sweep of the drain that would cause this? they both work fine independently but the one that is not used will lose a little water in the bowl each time the other is used. the sweep in in the kitchen ceiling and then turns about 1 or 2 feet to the wall and then down. there is not another air trap other than in the toilets is there? what can be done to fix this problem?

i.m.plummin
Re: totally baffled

What size is the vent. 4" I suppose. You could camera inspect the drain and vent If there is a slowdraining clog it could siphon the bowls $$$ I know :( but it sounds like you have bottomed out. You said they both do it and didn't mention water so I don't suspect a cracked bowl. Other than that I don't know.

Coupe
Re: totally baffled

the vent on the roof is 2". it appears to be clean well past the second story connection. would a clog or obstruction below the second floor (past the connecting sweep of the toilets) cause a suction in the other toilet. it dosn't seem logical to me but then i;m not a plumber.

JLMCDANIEL
Re: totally baffled

It is possible that the vent is not connected at the right spot.
Jack

Coupe
Re: totally baffled

what would be the wrong spot? dosn't the vent just have to be up stream of the toilets?

JLMCDANIEL
Re: totally baffled
Coupe wrote:

what would be the wrong spot? dosn't the vent just have to be up stream of the toilets?

Here's a simple drawing.
Jack

Attachment: 
i.m.plummin
Re: totally baffled

Wish I could be more helpful but without seeing it, it is the best I can offer.

I'll second that. If you can load pics that would be very helpful.

And, no the vent doesn't have to be upstream and shouldn't be unless there is another fixture washing the vent. The vent could be flat off the wye or downstream of the toilets. Or stacked on a cross.

If ther is a clogg downstream the water can fill the line to above the vent creating a syphon and as the fluid drains water syphons out of the other bowl.

Coupe
Re: totally baffled

thanks for the drawing. it looks like it is plumbed properly. we ran water down the vent pipe to the toilets from the roof with no problem. another vent pipes about three feet from the toilet vent pipe is just above shingle height ( not the standard 10 inches like the others) .when we ran water down it the water leaked through the kitchen ceiling causing us to cut out where the drains are connected.why would there be a open pipe through the roof? both toilets sweep into one downspout with a vent above the sweeps. any other suggestions before we cut into the wall in the bathroom? this is a relatively new problem in an older home. my buddy has lived in it for over 20 years and the problem just started about 6 months ago.

i.m.plummin
Re: totally baffled

Does the open vent look broken in the wall. It could be an abandoned penetratrion But your buddy would probably be aware of any remodeling around the area. Is it convenional or basement accessable underneath. Have you cabled the drain yet. The blue and orange boxes rent them just get a little training first make sure you where heavy leather gloves and make sure you get the cable guide. The attachments come with the rental. run the retriever first ( looks like a wire tornado ) and run it again with some scraper spoons while flushing with water.

goldhiller
Re: totally baffled
Coupe wrote:

we ran water down the vent pipe to the toilets from the roof with no problem. another vent pipes about three feet from the toilet vent pipe is just above shingle height ( not the standard 10 inches like the others) .when we ran water down it the water leaked through the kitchen ceiling causing us to cut out where the drains are connected.why would there be a open pipe through the roof? both toilets sweep into one downspout with a vent above the sweeps. any other suggestions before we cut into the wall in the bathroom? this is a relatively new problem in an older home. my buddy has lived in it for over 20 years and the problem just started about 6 months ago.

When you cut things open...did you see where the water leaked from this "other" vent stack?

I'm wondering if this "other" vent stack is/was also connected to these toilets (affording more intake air)...and is now plugged with gunk...and rotted out at an elbow or similar as a result...resulting in the leak you discovered.

Tore an older non-functioning vent stack apart about a year ago to find it completely clogged/packed tight with gunk (leaves,airborne dirt, dead birds, & whatever) for about 18" in length. Could't get it snaked or jetted from the roof because the impaction was that severe. The gunk looked as if someone had purposely packed it with yellow clay, but the very location of the impaction eliminated the possibility of that. The pipe was also rotted out just above this impaction from all the standing rainwater it had collected for years, maybe decades, on end.

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