toilet bowl leaks to empty in 30 min, starting at normal level Updated with latest!

[etbrown4]

I posted a similar thread a few weeks ago, but it got off into a discussion about good and not-so-good toilets, so I thought I'd start a new one to save folks from reading all that history.

Here goes:
Are there any other possible causes of a bowl leaking down to bone dry in 30 minutes, other than a clogged vent, or a possible leak in the internal trap itself?

Zero moisture shows up in the ceiling below.

Tips appreciated.

It's a $6-800 Black Amer Std "Savona" toilet.

.....................And the Update:

Initially we thought we had a leak out of the bottom through a hairline crack................ but maybe not! BTW,

We tried the very clever idea of inserting the clear tubing through the trapway, and no difference.
The vent through the roof is totally clear.

So we pulled it out and set it up high off the ground so we could refill the bowl and observe.

What we found, blows our mind! With 16 ounces of water in the bowl there is no leak. With 24 ounces in the bowl it leaks out of the main toilet outlet with a pretty good drip drip drip. A normal bowl level for this unit is probably around 40 ounces or so, and 2-3" higher water level, than the level with just 16 ounces of water in the bowl.

I'm 99% sure, with just 24 ounces of water in the bowl, it's not leaking through the main trapway. There is a 3/4" factory hole extending toward the front of the toilet, located maybe 2" above the bottom of the round outlet at the bottom of the bowl. Looking at the toilet turned upside down, you can see that there is a small passageway coming from that front side and connecting underneath into the main bottom outlet.

Not sure the purpose of that small passageway, but I'm pretty sure that the leak is taking that route. If so, it's hard to understand, but there is a definite leak, even at very low water levels in the bowl. It's hard to imagine that it was this way when it left the factory but I guess it's possible.

Ideas still appreciated!

PS. The bone dry trapway reported earlier may have been due to some unusually high winds, encountered earlier, though now not a factor. Once the water level got way low, it was probably easy for the howling wind to pull air inside the house through the trapway up through the vent, and dry it out.

[jadnashua]

A toilet will flush without a vent. A clogged vent will NOT siphon a toilet dry. Air movement in a vent can rock the water in the toilet, but would not siphon it dry. The rocking could cause some to slosh over the outlet weir, but it would take some really high winds to affect the level much. That hole may have been for hot gasses to escape during the firing in the kiln...it likely should have been plugged prior to leaving the factory, and it may be that it was not done properly and fell out sometime and you noticed the level drop.

Replace the toilet, or if you're feeling lucky, try plugging that hole. But, if you saw a hairline crack, stop wasting your time and replace the bowl, or better yet, the whole thing.

[etbrown4]

What seemed like a faint hairline crack was in the bottom of the trapway, but upon closer examination, I think it's something in the original china that's ok. That portion of the trapway is dry when the leak is active.

With regard to that 3/4" hole Ii looks like it's an important part of the design. There seems to be a definite sealed channel or port in the underside of the bowl that appears to be a route for that hole, possibly to feed out to the bottom of the toilet. I have no idea what the purpose might be, but I bet we can figure this one out

I suppose I could drain the bowl and put some duct seal in the 3/4" hole for a test!

[jadnashua]

If that hole is facing the bowl's outlet, it should be there as it's the outlet that starts the siphon effect when you flush the toilet.

[etbrown4]

If that hole is facing the bowl's outlet, it should be there as it's the outlet that starts the siphon effect when you flush the toilet.

We have two of these Amer Std one piece 'Savona' toilets in the same house.

Interestingly, one has the 3/4" hole as described earlier and the other does not!

It is clear that Amer Standard has different internal porting , even on toilets that look the same outside.

I'm sure that jadnashua knows his stuff, however it appears that there must be several ways to design a toilet, and I guess they both work, or either they used to.

[jadnashua]

There are basically two types of toilets over the years that have been commonly sold in the USA - washdown and siphon jet (my terms - not to be confused with bowl wash technique). The older ones with washdown technology generally required lots of water to be dumped to generate enough pressure to create the siphon effect that eventually emptied the bowl. The newer ones generally use a jet of water, pointed at the outlet, to almost instantly create the siphoning effect. This can be done with MUCH less water, but the fluid dynamics are much more critical - design is as important as quality of construction (AS qa is sometimes lacking from reports here). There are several ways to create the required jet velocity and pressure: a taller tank, pressure assist, or more water (flushometer valves which require large supply lines often found in commercial buildings). When the water use restrictions started to come into play, those that had a decent washdown tried to create the same effect with less water and it was often a dismal failure. Most eventually changed their designs. Not all have kept up their QA/QC, and what may be a decent design can have a spotty performance in real life. To create a siphon jet requires more well designed and contructed internal passageways in the toilet where there are more chances of defects since they are hidden from view.

Regardless of all that, if your toilet leaks internally, replace it, preferably with one with a better design AND construction quality.

[wjcandee]

Maybe it's just me, but...

I have been lurking on this thread for a while. I haven't said anything because I don't really get the discussion. But now, I just can't bite my tongue...

You have two of the identical toilet. One leaks, one doesn't. The one that leaks has a hole in it that the other one, which doesn't leak, does not. Am I following this?

If so, the hole is not a design difference in the same model, it's a defect or a manifestation of a defect. Send it back or take it back and get one that doesn't leak.

[etbrown4]

Both units are the Savona model by American Standard, however the production dates are about 6 months apart and there are distinct differences.

The thickness of the china is much different in several places, and of course one has that pesky 3/4" factory hole as described and the other does not!

Jim's idea, as I hear it, may be that the 3/4" hole might pertain to a siphoning effect, and that sounds spot on to me.

2 questions remain (and possibly these are for an engineer at A/S) -

1. What is the design water level height on a bowl like this one? As described before, at about 3" above the absolute bottom, it's not leaking, but at another inch higher, it leaks. That 16 oz of water just can't be what A/S had in mind as the proper design height for water in the bowl, as it's hardly any. IE, if the lousy 16 oz of water is supposed to represent the normal bowl height, then one could argue that there is no leak at that level! So the design level is of key importance.

2. The other question is, assuming that Jim is right, that the 3/4" hole may be a siphoning hole, then what keeps this unit from leaking down to that height shortly after every flush? Initially there seems to be a typical volume of water in the bowl like 40oz or so, but after 30 min. it leaks down to just 16 oz left.

Tomorrow I'll see if I can reach a technical person at A/S, but usually all I ever get is a customer service, nonetheless I'll try again.

[jadnashua]

A toilet bowl is sort of like a teakettle...you can only fill it so high before it leaks out the spout. On a toilet, that outlet is called a weir. Regardless of what you do, unless the drain line is clogged, you can never keep a toilet full of water higher than the outlet of the weir. The siphon jet is connected to the toilet's tank, and when you open the flush valve, some water goes down the path to the siphon jet to start the flush, some goes out (normally) the rim to wash the bowl down, and after the flush valve closes, water goes down the overflow to refill the bowl. Most US style toilets have a moderate water spot, but it is dictated by the design and quality of construction can cause that level to vary on the same models. For a toilet to work as designed, each model will have a predetermined quantity of water in the bowl prior to flushing. Any excess will drain out over the weir and down the drain.

Manufacturers make running changes in models all the time. They may also make the same models in various factories. So, differences may not represent a defect. If that were mine, I'd just trash it and replace it with a new one. It's not worth the aggravation. A toilet that doesn't have the design level of water in the bowl will not flush well. A poorly designed toilet may never flush well. A well-designed toilet that is defective may not flush well.

[wjcandee]

So, differences may not represent a defect.

From an engineer's perspective, of course this is correct. And correlation in time doesn't mean causation. Etc.

However, he has a toilet that drains all the water out of the bowl, to the point of being dry, in 30 miinutes after it refills. It's not a siphon. It's a defect. So the toilet is defective.

Perhaps a more precise way to say it is: Using an Occam's Razor approach, given the available information, the first thing one should investigate is whether the differences in the two are reflective of a defect.

But since it's obviously-defective, regardless of what that defect is, it is time, as you point out, Jim, for the member to return it and get one that works. The rest is just intellectualization.

[etbrown4]

The plot thickens a bit. It seems that the 5/8"-3/4" holes are common.

We just checked two other toilets - a Kohler and a Mansfield. Both have the same identical 5/8" or 3/4" hole, located in the small diameter portion of the bottom of the toilet bowl. As with the Amer Std. toilet, the hole points toward the front of the toilet and located in the vertical section... just an inch or so from the bottom.

It makes sense that this would be connected to the tank, however when we turned the Amer Std unit over, we observe a built out, or layered over area that looks like a port or passageway, extending from the lower portion of the front of the bowl, down to the main trapway outlet. Possibly this built out passageway is not related to that hole! don;t know.

Though we don't know what this connects to, it will be interesting to see what Amer Std says about the drip which is seemingly coming this way, and not coming from the trapway or weir.

If we get an answer, we'll post it.

[jadnashua]

(Nearly) all modern US toilets have a hole down low in the bowl, pointed towards the outlet to help start the siphon. The size, exact location, and quality of its operation varies. It is designed to help start the water/waste moving in the right direction - i.e., towards the outlet, over the weir. Something needs to overcome the inertia. On an older, high volume toilet, it filled up with lots of water, and that big volume of water in the bowl then had enough oomph to start it to flow out over the weir with some force. Today's requirements no longer make that possible or preferable. the flush cycle on a modern toilet is over before an older one even had a chance to empty the tank into the bowl. Another reason why a larger flapper valve is used on most modern toilets...lots of water fast. On an older one, it didn't really matter.