Toilet dries out.

Zman

I am doing some sleuthing for a large condo complex where an owner complains that his toilet is dry when he comes back after being away and the unit smells.

I marked the water level of the toilet and then had an assistant run water and flush the toilets in any unit that could possibly be on the same stack.

When the toilets on the lower floor were flushed, there was a gentle wave action from front to back of the bowl and the level of the water would drop ~1/8". After doing this several times, the drop would increase to ~3/8", and eventually, the trap was not sealed.

Based on the layout, I made an educated guess that the toilet was wet vented through the sink and I piped smoke into the sink's San-Tee. I then went on the roof and observed the vent stack where the smoke was coming from. When my assistant flushed the toilet, I could see the smoke pull back momentarily.

I think my next steps will be to camera the vent from the roof and look for partial obstructions. I will also try to camera from the sink down to the toilet and look for something there. From the toilet piping, I should be able to see if the vent is clear where it ties in.

I did notice that the toilet having the problem is a very low model and am wondering if the trap design is part of the issue. This is the toilet https://www.us.kohler.com/us/san-souci-one-piece-round-front-1.28-gpf-toilet-w-aquapiston-flushing-technology/productDetail/toilets/1077803.htm

Does anyone have thoughts on this one?

mattmia2

Before i got to the bottom I was thinking is there a toilet with a more robust trap sort of the equivalent of putting a drum trap on an s trap so there is more water so maybe air gets sucked in but it doesn't empty the trap.

Jamie Hall

How does the toilet drain hook into the main stack? I've had trouble with those newer toilers either pulling the trap --what you're seeing --or almost worse, not flushing, if there is any obstruction to speak of on the line going to the main stack for the cluster.

STEVEusaPA

What's the minimum they have been away and it happened? Is it happening to anyone else?
Where is there toilet in relation to the others and the main stack/vent?

To me, seeing the smoke pull back in is just natural vacuum.

Is this toilet on a top floor? Even if it's not, maybe the vent is partially clogged or undersized.

pedmec

sounds like your toilet is not vented. your creating a vacuum in the stack which is tilting the trap seal in the toilet. if it was truly wet vented then the wet vent would break that vacuum. that's why plumbing vents are part of the plumbing system. it would be hard to believe that if the bathroom below was vented properly it would effect yours. I've seen water seals in toilet bowls move a little with huge gust of winds but not a properly vented toilet trap get tilted to the point of losing the trap seal. traps in toilets are pretty deep. a lot of toilets you can see the trap design if you look on the side.

anything is possible but unless there is a defect in the toilet i would venture there. i don't know how old your building is but check to make sure all caps were remove from the top of the stacks. iv' seen guys air test stacks and forget to remove the test caps after they are done. could be as simple as that.

Dave Carpentier

What if you watch the lower floor's toilet water level while you flush the upper floor toilet multiple times ?
Could the whole building be experiencing some level of the same effect , but using the toilets more often (the customer's complaint is dry trap after he's been away) ?

Zman

STEVEusaPA said:

What's the minimum they have been away and it happened? Is it happening to anyone else?
Where is there toilet in relation to the others and the main stack/vent?

To me, seeing the smoke pull back in is just natural vacuum.

Is this toilet on a top floor? Even if it's not, maybe the vent is partially clogged or undersized.

You can watch the level drop with each flush. Under the right circumstances, the trap can be mostly empty in an hour.

I don't have buildng plans but based on the location of the vent, I believe there is a common vent shared by 2 adjacent units for all 5 floors.The unit with the problem is on the 4th floor. My mind's eye makes me suspect a partial obstruction between the 4th and 5th floor.

mattmia2

Do the other units have the same model toilet? What happens in the other uhit on the floor?

pedmec

when you say empty in a hour. is that without using the toilet. or is it because the tipping water line.

Zman

@pedmec Every little wave action takes a bit of water with it. When the toilet is not being used, but the ones on the lower floors are, this toilet loses most of its water.

@mattmia2 This toilet is different than the others. The water does not drop on other toilets observed on the same stack.

mattmia2

Maybe time to ask kohler about it.

Shane_2

I would suggest- Pull the toilet, put it up on blocks(bricks, bucket, whatever), just make sure it's level. Slowly pour water in from a bucket till the trap is full. Wait a little while and check for leaks with a flashlight. I have had more than one over the years with bad casting. Many of the manufactures use caulk that fails when new or years later

HydroNiCK

The system wasn't piped right.  When The bowls flush the slug of water traveling down the drain passed each connection to the stack siphons the traps.

Zman

HydroNiCK said:

The system wasn't piped right.  When The bowls flush the slug of water traveling down the drain passed each connection to the stack siphons the traps.

The traps are not leaking and the main vent is not plugged. We are going to jet the wet vent through the sink and see if there is a partial obstruction there. I kind of double that the installation is incorrect, but anything is possible. The building was engineered and inspected and the pipes that are visible are correct.

Thank you for the suggestion.

HydroNiCK

Zman said:

The system wasn't piped right.  When The bowls flush the slug of water traveling down the drain passed each connection to the stack siphons the traps.

The traps are not leaking and the main vent is not plugged. We are going to jet the wet vent through the sink and see if there is a partial obstruction there. I kind of double that the installation is incorrect, but anything is possible. The building was engineered and inspected and the pipes that are visible are correct. Thank you for the suggestion.

Are the bowls connected using double fixture fittings or double wyes and 8th bends?

Zman

HydroNiCK said:

Zman said:

HydroNiCK said:

The system wasn't piped right.  When The bowls flush the slug of water traveling down the drain passed each connection to the stack siphons the traps.

The traps are not leaking and the main vent is not plugged. We are going to jet the wet vent through the sink and see if there is a partial obstruction there. I kind of double that the installation is incorrect, but anything is possible. The building was engineered and inspected and the pipes that are visible are correct.

Thank you for the suggestion.

Are the bowls connected using double fixture fittings or double wyes and 8th bends?

No, they are not. They appear to be plumbed like a typical bathroom group with the lav being used as a wet vent. I suspect a partial obstruction where the wet vent ties in.

Lyle {pheloa} Carter

If you read deeper into the instructions on the installation of this toilet, like many new toilets. When installing on a back to back installation. The two toilets cannot be installed on a double sanitary tee, but must be installed on a double wye with 45°s. If the other toilet is also of a type that must be installed on a double wye, the water when flushed will come directly across the double sanitary tee fill up the closet bend and then empty with a vacuum draining off some of the water from the toilet.

Zman

Lyle {pheloa} Carter said:

If you read deeper into the instructions on the installation of this toilet, like many new toilets. When installing on a back to back installation. The two toilets cannot be installed on a double sanitary tee, but must be installed on a double wye with 45°s. If the other toilet is also of a type that must be installed on a double wye, the water when flushed will come directly across the double sanitary tee fill up the closet bend and then empty with a vacuum draining off some of the water from the toilet.

It's not a back to back connection.

Big Ed_4

If the owner is away for long periods of time the water could evaporate . One fix wrap the toilet with saran wrap . A drip valve can be used for the other traps and maybe the toilet. They are used for washermachine overflow catch basin to keep the trap filled.