Our house was built in 1987. We have two toilets back-to-back on the second floor connected to the same sewer pipe. The toilets functioned ok. Recently, we remodeled the two bathrooms and installed two Kholer toilets Model numbers K-3888 and K-3978. Now, when the downstream toilet is flushed, it sucks water out of the other (little by little over several flushes) leaving a small amount water in the upstream toilet. This never happened with the original toilets. Why is it doing this now? How can I repair it?
BackoTo-Back Toilets
- Thread starter Ibex2
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more aggresive flush of new toilets, possiblle different flushing design like a syphon jet ( havent looked at the models yet ) and lacking a proper vent would all cause this problem and us why this is not allowed by code. you could remedy this by installing proper venting.
Thank you. You have given me enough information so that I won't be intimidated when I talk to the contractor. The toilets do seem to have a more aggressive flush. Maybe I can find one that isn't as strong. Note: the toilets were installed by a professional licensed plumber. One would hope that he followed code.
he wouldnt have had considerd code much likely, if his scope of work was to install the toilets then thats what they did, if he was to do anything with the dwv piping then he would be required to bring it up to code. a vent installed on the trap arm of the syphoning toilet woule eliminate the problem .
The more proper term is "Air Admittance Valve". Basically, a check valve that will open to allow air to be sucked into the drain piping, but is normally closed to prevent sewer gas from being let out of the drain piping.
In your case, it would allow air in to relieve the vacuum that is created in the second toilet drain line when the first one is flushed.
In your case, it would allow air in to relieve the vacuum that is created in the second toilet drain line when the first one is flushed.
this would work, but not be as ideal as running a vent line. One would have to see the house and crawl space ( or basement ) and also into an attic. More work, cost etc. but better overall.
What exactlly is his plan for the cheater vent ? He would have to come off of above the top of the Toilet trap arm to achieve a proper installation of a AAV. on a line, which means access into a wall somehow... or a cabinet.... see where im going with this ???
So, back to back toilets, one syphons the other.. so where are the lavs ?
one lav for each bathroom I assume ?
....... I would look to see whats connected to what, there is no reason that The branch for the lav shouldnt be a wet vent for the Toilets.'
What exactlly is his plan for the cheater vent ? He would have to come off of above the top of the Toilet trap arm to achieve a proper installation of a AAV. on a line, which means access into a wall somehow... or a cabinet.... see where im going with this ???
So, back to back toilets, one syphons the other.. so where are the lavs ?
one lav for each bathroom I assume ?
....... I would look to see whats connected to what, there is no reason that The branch for the lav shouldnt be a wet vent for the Toilets.'
Thank you for the comments. The plumber came in and did some tests and said it was a venting issue. The air admittance valve will not solve the problem. He is mystified because when he installed the toilets and shower fixtures, he checked the pipes and vent. Everything was correct. He also climbed on the roof and said that the vent was open. He is returning this afternoon with a camera.
That is a common problem with Toto toilets when piped with a DBL fitting. Toto even has a warning about it. I'm not sure if American Standard and Kohler have the same warning but they should. They must be piped with a DBL Y. If you have from the up stream side a toilet then vent fouled by a second toilet in less then 48" on a horizontal run you will have the problem you are experiencing.
John
John
I understand what you mean by a double Y fitting, but I dont think it will work in this situation. These toilets are on the second floor and there is no wall beneath them that could run a waste pipe. The master bath toilet discharges into a waste pipe (90 degree elbow) that runs behind the toilet, through the wall where it is vented, continues into the second bathroom where the toilet discharges into the same pipe (probably Y fitting). The pipe continues about 9 feet through the second bathroom, across the hall then down.
With the way that is piped you will continue to have problems with the toilet. Adding vents will do nothing to solve your problem. I blame the manufactures of the toilets for not making this problem more well known. I'm sure in time codes won't allow this type of setup for back to back toilets. There are many plumbers that are not aware of this until they try install new toilets on this back to back setup.
John
John
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im back to thinking this isnt vented properly, by this discription. if that distance beyind the 2nd toilet could plausiblly be more like 12 feet ( am thinking it could since the lav waste pipe would be the effective wet vent distance ) then you could be simply inducing a small syphon. this would have to be circuit vented properly in order to work. Would have to see the dwv layout to know for sure, bit Ive seen this layout work with proper venting installed. this could even properly be achieved with 2 seperate branches and bathroom groups. perhaps im mistaken here but from your piping discription it doesnt sound like theyre actually back to back ?? forgive me if im waaaay off..... Time for bed
Joeypipes23
Member
Ibex2 said:
Definitely a venting issue