Water Closet Tolerances
November 1, 2009
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Vitreous china is strong, but an out-of-tolerance
water closet can fail.
I was speaking to a friend who works for a manufacturer, which will go nameless, regarding wall-hung water closets. The discussion centered on leaks and fractures.
Of course, wall-hung water closets are not supposed to leak when they are installed. We sort of know that in this industry. Furthermore, wall-hung water closets are not supposed to crack or fracture. Again, we know that vitreous china is extremely strong. It doesn’t fracture too easily.
As you know, a water closet carrier can have a plastic horn or a cast-iron horn when connecting to a water closet. Whether plastic or cast iron, the horn should never come in contact with the water closet. There is a seal between the horn and the water closet that prevents the leaks.
The wall-hung water closet is designed to flex when used. The amount of flex depends on the weight of the person using the water closet. The heavier the person, the more flex in the connection between the water closet and the carrier. This is why there is a space required between the wall and the water closet. If the water closet is tight to the wall, there is no flex possible and the water closet and wall will take the brunt of the weight. The installation is designed to have all of the weight distributed to the carrier, which transfers the load to the floor.
If the water closet comes in contact with the horn, it is a recipe for disaster. If the horn is plastic, the likely scenario is that the seal between the water closet and the horn (and wall) will leak. The vitreous china is stronger than the plastic; hence, when they do battle, the vitreous china will win.
When a cast-iron horn is used, the battle is somewhat different. Cast iron will win out over vitreous china. The result is the water closet will fracture around the horn connection.
The first possibility is always improper installation. When installing a wall-hung water closet, the vitreous china should be resting on the studs (or bolts) of the carrier. Looking at the studs, there should be no gap between the top of the bolt holes in the vitreous china and the stud. If the china does not rest on the carrier studs, it means the water closet horn is supporting the water closet. As previously mentioned, this is a recipe for disaster.
It is also possible that, no matter how you align the water closet, all of the bolt holes in the vitreous china do not rest on the carrier studs. When this happens, the product tolerances are off. That means either the carrier is out of tolerance, or the water closet is out of tolerance.
If you were going to bet money on it, I would always place my bet on the water closet being out of tolerance. There is a simple reason why: It is tougher to meet the tolerances with vitreous china than it is with a carrier.
Vitreous china is a very unique material. The reason vitreous china is used in plumbing is because the china is nonporous. You cannot glaze every surface in a water closet. For that matter, you cannot glaze every surface in other vitreous china plumbing fixtures.
The reason vitreous china is nonporous is because it shrinks during firing to make it leak-proof. A water closet shrinks 12.5 percent when it is fired in the kiln. That means water closet designs are actually 114 percent larger than the finished product.
Ceramic engineers always claim that no two water closets are identical because of the shrinkage factor. While they may not be identical, they are awfully close.
Anyway, getting back to the tolerances, it is possible that, during the manufacture of the water closet, the bolt holes go out of tolerance. The result is that the vitreous china will not rest on all the studs when mounted on a carrier.
If you don’t trust the carrier, try another carrier. If the vitreous china still doesn’t rest on the studs, the water closet is out of tolerance.
There is no requirement in the fixture standard to check the tolerance of every water closet’s bolt holes. Hence, there is a possibility the water closet is shipped out with the holes improperly placed.
When you encounter a water closet that is out of tolerance on the bolt holes, return it to the supply house for credit. Make sure you show them how the holes are out of tolerance. The manufacturer will always make good on an out-of-tolerance water closet.
If you encounter a leaking wall-hung water closet, before you reinstall the same water closet, check the tolerance of the bolt holes. If the vitreous china does not completely rest on the carrier studs, don’t reinstall the water closet. Again, bring it back for credit, even if it is many years old.
For water closets that have cracked or come off the wall, before you throw them in the garbage, check the tolerance of the bolt holes. If they are off, you know what to do.
Many contractors naturally assume that a water closet that has come off the wall is due to vandalism. While vandalism is definitely a possibility, an out-of-tolerance water closet is also a possibility. The only way to find out is to check how the water closet sits on the carrier.
You want to be known for a perfect installation. You need perfect products for that assurance.
I was speaking to a friend who works for a manufacturer, which will go nameless, regarding wall-hung water closets. The discussion centered on leaks and fractures.
Of course, wall-hung water closets are not supposed to leak when they are installed. We sort of know that in this industry. Furthermore, wall-hung water closets are not supposed to crack or fracture. Again, we know that vitreous china is extremely strong. It doesn’t fracture too easily.
As you know, a water closet carrier can have a plastic horn or a cast-iron horn when connecting to a water closet. Whether plastic or cast iron, the horn should never come in contact with the water closet. There is a seal between the horn and the water closet that prevents the leaks.
The wall-hung water closet is designed to flex when used. The amount of flex depends on the weight of the person using the water closet. The heavier the person, the more flex in the connection between the water closet and the carrier. This is why there is a space required between the wall and the water closet. If the water closet is tight to the wall, there is no flex possible and the water closet and wall will take the brunt of the weight. The installation is designed to have all of the weight distributed to the carrier, which transfers the load to the floor.
If the water closet comes in contact with the horn, it is a recipe for disaster. If the horn is plastic, the likely scenario is that the seal between the water closet and the horn (and wall) will leak. The vitreous china is stronger than the plastic; hence, when they do battle, the vitreous china will win.
When a cast-iron horn is used, the battle is somewhat different. Cast iron will win out over vitreous china. The result is the water closet will fracture around the horn connection.
Take A Closer Look
The question you may be asking is, “Why would the horn come in contact with the water closet?” Or better yet, “How is it that the water closet comes in contact with the horn?”The first possibility is always improper installation. When installing a wall-hung water closet, the vitreous china should be resting on the studs (or bolts) of the carrier. Looking at the studs, there should be no gap between the top of the bolt holes in the vitreous china and the stud. If the china does not rest on the carrier studs, it means the water closet horn is supporting the water closet. As previously mentioned, this is a recipe for disaster.
It is also possible that, no matter how you align the water closet, all of the bolt holes in the vitreous china do not rest on the carrier studs. When this happens, the product tolerances are off. That means either the carrier is out of tolerance, or the water closet is out of tolerance.
If you were going to bet money on it, I would always place my bet on the water closet being out of tolerance. There is a simple reason why: It is tougher to meet the tolerances with vitreous china than it is with a carrier.
Vitreous china is a very unique material. The reason vitreous china is used in plumbing is because the china is nonporous. You cannot glaze every surface in a water closet. For that matter, you cannot glaze every surface in other vitreous china plumbing fixtures.
The reason vitreous china is nonporous is because it shrinks during firing to make it leak-proof. A water closet shrinks 12.5 percent when it is fired in the kiln. That means water closet designs are actually 114 percent larger than the finished product.
Ceramic engineers always claim that no two water closets are identical because of the shrinkage factor. While they may not be identical, they are awfully close.
Anyway, getting back to the tolerances, it is possible that, during the manufacture of the water closet, the bolt holes go out of tolerance. The result is that the vitreous china will not rest on all the studs when mounted on a carrier.
If you don’t trust the carrier, try another carrier. If the vitreous china still doesn’t rest on the studs, the water closet is out of tolerance.
Out Of Tolerance
Realize that today we live in a global economy. Vitreous china water closets are made all over the world. As a result, the inspection process may be different from one plant to the next. It is possible they don’t always check the tolerance of the bolt holes on wall-hung water closets.There is no requirement in the fixture standard to check the tolerance of every water closet’s bolt holes. Hence, there is a possibility the water closet is shipped out with the holes improperly placed.
When you encounter a water closet that is out of tolerance on the bolt holes, return it to the supply house for credit. Make sure you show them how the holes are out of tolerance. The manufacturer will always make good on an out-of-tolerance water closet.
If you encounter a leaking wall-hung water closet, before you reinstall the same water closet, check the tolerance of the bolt holes. If the vitreous china does not completely rest on the carrier studs, don’t reinstall the water closet. Again, bring it back for credit, even if it is many years old.
For water closets that have cracked or come off the wall, before you throw them in the garbage, check the tolerance of the bolt holes. If they are off, you know what to do.
Many contractors naturally assume that a water closet that has come off the wall is due to vandalism. While vandalism is definitely a possibility, an out-of-tolerance water closet is also a possibility. The only way to find out is to check how the water closet sits on the carrier.
You want to be known for a perfect installation. You need perfect products for that assurance.
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