Dreaded back to back high power flush toilet question.

[Scott Chambars]

I have read most of the posts on this. My 90 year old father paid to have 2 Toto toilets installed . In an older apartment. First C then D. They are back to back. Now the 2 toilets are fighting each other. Vents are clear. When one is flushed the other receives a big ball of air then the water drains out of trap. Is there a new toilet on the market that will work with the old pluming that you could suggest using. Tearing up the cement slab is to costly.
Thanks

 

[Jadnashua]

Older toilets tended to flush very slowly, and it worked because they used lots of water. Pretty much all newer toilets must flush quite fast in order to flush with the required maximum water volume. Toto's installation instructions specifically call out that you'll have problems if you do not have the proper fitting when they are back-to-back. Check out page two of one of their spec sheets, and this is true for pretty much ANY new toilet.

https://terrylove.com/pdf/cst744sl.pdf

Unfortunately, I do not know of any new toilet meeting the federal mandates on maximum water usage that would be much, if any, better without changing the fitting.

 

[Sponsor]

 

[Scott Chambars]

Older toilets tended to flush very slowly, and it worked because they used lots of water. Pretty much all newer toilets must flush quite fast in order to flush with the required maximum water volume. Toto's installation instructions specifically call out that you'll have problems if you do not have the proper fitting when they are back-to-back. Check out page two of one of their spec sheets, and this is true for pretty much ANY new toilet.

Thanks Jim. Yes I read that in the Toto instructions. I was wondering about going back to a small throat with a flapper. Is there any toilets that sill swirl the water out of the bowl instead of one big gush?

 

[Jadnashua]

TO get enough head pressure to start a siphon, you need a fair amount of water in the bowl...IMHO, lots more than the federal mandate allows. So, I do not think you'll find a new toilet that meets the federal guidelines (and is thus legal to install) that doesn't have much more velocity than the older ones. Most of the new ones use s siphon jet to get the siphon started. The pressure assisted ones dump the water under pressure, verses gravity, so those might even be worse.

Terry might have some ideas, since he sees much more in the real world, but from what I've read, I don't think there's an easy solution. A lazy flush with the limited volume of water implies lousy evacuation of the bowl.

 

[Scott Chambars]

TO get enough head pressure to start a siphon, you need a fair amount of water in the bowl...IMHO, lots more than the federal mandate allows. So, I do not think you'll find a new toilet that meets the federal guidelines (and is thus legal to install) that doesn't have much more velocity than the older ones. Most of the new ones use s siphon jet to get the siphon started. The pressure assisted ones dump the water under pressure, verses gravity, so those might even be worse.

Terry might have some ideas, since he sees much more in the real world, but from what I've read, I don't think there's an easy solution. A lazy flush with the limited volume of water implies lousy evacuation of the bowl.

What about something like the American Standard Vormax?

 

[Scott Chambars]

What about something like the American Standard Vormax?

OK just read the online installation guide. It has the same back to back warning.

 

[Jadnashua]

As I said, to get decent performance with the limited water allowed, the toilets MUST flush faster than the old toilets that used sometimes 4x more water. So, what worked on an old one often does not work with the new. There's a reason why they recommend that fitting, it makes it nearly (nothing's impossible) to cause skipover to the opposite branch. Plumbers tended to use the older one because it is more compact, and easier to install on that installation, but it still should have been the Y.