Mansfield Alto 137/173 Bad Flushing

[BobN]

In our new house, the builder installed Mansfield Alto 137/173 toilets over cheap offset flanges. The flush valve is FLUIDMASTER 400 Model Anti-Syphon. The house is built on a slab, and the drain pipes are cast into place. They couldn't get the drain in the perfect location during concrete pour. That's why they used offset flanges.

Since new, they have all had the same issue. On random occasions, they don't flush well. Bowl water level will back up, then slowly percolate out, while solids remain in the bowl. The next flush is no better. It isn't a function of the amount of solid waste or waste fluid in the bowl. I've tried plunging the bowl and cleaning the mouth of the trap with a brush. That doesn't help.

Out of caution, we've stopped flushing any toilet paper, but we still have the issue. What sometimes fixes it is quickly pouring a bucket of water into the bowl, forcing a quick purging of the trap. But that's not a consistent fix.

Is it possible that air is getting into the trap and preventing a correct flush? What else could be wrong?

In the tank, I see a line on the center tube market "Fill Line" and water is right up to that line. Do these toilets have another adjustment that might help?

I know that Mansfield toilets don't have the greatest reputation. I know that offset flanges can be troublesome and that some are better than others. Is this simply the result of multiple bad practices?

Is there anything I can do to help, other than replacing the toilets?

Thank you.

 

[Breplum]

The Alto has a very good 1,000 grams MaP performance score, so it is not the WC unless defective or has a toy trapped.
I wonder what the toilet vent looks like and the drain itself for that matter.

https://map-testing.com/wp-content/uploads/2024/02/2024-02-02-All_tank-type_toilets.pdf

 

[Sponsor]

 

[BobN]

I read about something scientists call Goodhart's Law. This principle says that when someone develops a way to measure performance with one number, people will develop a way to score really high in the test without concern for actually making the world better, so that measure becomes worthless.

Goodhart's Law

One of Peter Drucker’s most known quotes is “If you can’t measure it, you can’t improve it.” It’s hard to deny that measurement and gathering data are critical factors to success, which is why Goodhart’s Law can be a harsh reality check. In the words of anthropologist Marilyn Strathern...

modelthinkers.com

MaP measures number of grams of waste eliminated per flush. My particular problem is not amount of waste removal. It's a problem that the toilet gets into a funk, so to speak, and takes cajoling (flooding with gallons of water) to make it work again.

 

[Breplum]

when we run into a suspect problem with a toilet, we pull it, and set up a bench test outdoors and evaluate the flush.
If it can't be replicated outdoors, then conclusion is simple: bad piping or venting.

 

[GReynolds929]

If a horned wax ring was used the horn could be partially blocking the offset opening.

 

[Eman85]

FWIW I installed a Mansfield Pro-fit toilet from Lowes as a replacement in my home. It works excellent and was installed when bathroom was renovated, system wasn't changed at all and previous toilet worked excellent also for 30 years. I'd go with the possible installation problem with wax ring or vent problem. Also FWIW I went with Mansfield because they cast in USA and I returned American Standard I had purchased due to very poor quality of the initial purchase the 2 replacements they sent me.