Back to Back Water Closet Issues - Existing 1973 Condo Reno

[JP-In-Naples]

I recently purchased a great little first floor condo in Southwest Florida. The building is a two story villa (12 units total) 3 units each first and second floor separated by courtyard. It was originally built in 1973 and complete renovation in 2012. We’ve now had time to spend in the condo and realizing issues with the toilet. Long story short from my research and inquiries appears that my unit has a shared back to back water closet with existing double sanitary tee connection in the slab. They tried to use new Koehler toilets high-pressure low volume and experienced spray problems. I’m told previous plumbing inspection in 2020 (camera scope) confirmed the use of double sanitary tee and clean (not blocked) shared vent stack. I’ve seen posts on this site that the correct install is the use of a double wye fitting. The mutual accepted fix was to replace each unit with a low volume/pressure toilet (Sterling). It appears it took care of the spray problem in the other unit, but my toilet continues to lose water whenever they flush to the point of a dry bowl - not good. There is extreme reluctance to jackhammer floor to replace proper wye fitting. Are there any other options I can recommend - I’m somewhat at a loss. I want to be afforded basic necessities that a proper functioning toilet should provide and not have to flush to fill up the bowl for use. Sure -vent air admittance valves or Studor pressure release valves - other toilets - other recommendations. I’m sure this has been resolved in other older buildings when the new toilet standards were invoked? Thanks in advance!

 

[Terry]

Toilets with the 3" flush valve or with Flushmate pressure assist would not be your friend there.
There are still some toilets that flush a bit slower using the old school 2" flush valve in the tank with flapper. The problem with some of the new toilets is the quick flush that skips over the cross and pushes a column of air up into the opposite bowl which winds up displacing some of the water in the bowl.

Which ones are those? Give us a few days to think about that.

 

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[JP-In-Naples]

Toilets with the 3" flush valve or with Flushmate pressure assist would not be your friend there.
There are still some toilets that flush a bit slower using the old school 2" flush valve in the tank with flapper. The problem with some of the new toilets is the quick flush that skips over the cross and pushes a column of air up into the opposite bowl which winds up displacing some of the water in the bowl.

Which ones are those? Give us a few days to think about that.

Thanks so much for the quick response - I’m meeting with the board and lay out the problem in detail on Thursday. These “old school toilets” you mention certainly might be an amenable option. I look forward to any additional help. Thanks again!!