What does that require? How do you know when to reconfigure, and when to just get a better toilet?
“What does that require? How do you know when to reconfigure, and when to just get a better toilet? “
I’ll usually reconfigure when I have a long horizontal run of 4” cast iron especially that is constantly backing up with a low flow toilet. On one such job I cut out the cast iron in a crawlspace and replaced it with 4” ABS and shortened up the run by using 45 and 22 degree fittings instead of right angle sweeps that were on the cast iron. This kept the drainage velocity up. I also pitched it more than the usual 1/4” per foot of run. This alleviated the problem. You are talking about major work though.
Other times I’ve actually reduced the diameter of the drainage to 3” for faster flow though this can be tricky.
Not sure what you mean by a “better” toilet. A 1.6 gallon flush is a 1.6 gallon flush as far as water volume being flushed down the piping goes. This is a problem that occurs in the actual drain piping not the toilet itself. Some people I will just recommend a double flush with solids no matter what. The toilet is functioning fine but the second flush clears the waste from the drainage piping downstream of the toilet.
Vertical runs of pipe usually are not an issue with these toilets unless that vertical run turns into a long horizontal run in the basement that gives the waste a chance to slow down and then start backing up.
I would be willing to bet most problems with these toilets would be alleviated if they didn’t go below 2 to 2.5 gallons a flush and left it at that. The new 1.28 GPF toilets will just make this problem worse.