What type of toilet do I have?

[sevensages]

TL;DR

Do I have a gravity-fed, rim-jet design toilet? Or do I have a gravity-fed, siphon jet toilet?

I was enrolled in an online plumbing course at Stratford University. My plumbing textbook lists four types of residential toilets: 1# upflush toilets 2# pressure assisted toilets 3# gravity-fed, rim jet toilets and 4# gravity-fed, siphon-jet toilets.

I know my toilet is not an upflush toilet because my toilet is not below the sewage line, and my toilet does not have a grinder and a pump next to it to propel waste upwards. I am about 99% sure that my toilet is not a pressure assisted toilet because I don't see any pump inside the tank of the toilet. All I see inside the toilet are the refill valve, the overflow tube, and the flapper. Here is a photograph of the inside of my toilet tank:

I think that my toilet is probably a gravity-fed, siphon jet toilet, but I don't know for sure. I think it is also possible that my toilet is a gravity-fed, rim-jet toilet.

Here is a photograph of the bottom of my toilet bowl:

There are two holes in the bottom of my toilet bowl. The hole on the right in the photograph is the hole that the waste goes through on its way to the p-trap and the building drain and then to the building sewer. The hole on the right in the photograph is a lot bigger than the hole on the left in the photograph. The hole in the right of my photograph is at the back of the toilet (closer to the tank of the toilet). If a person was peeing into the toilet, the hole on the left in the photograph is closer to where that person would stand. The existence of that (little) hole on the left in the photograph makes me think that I probably have a gravity-fed, siphon jet toilet. I don't think that my toilet is a gravity-fed rim-jet toilet because I don't think that gravity-fed, rim jet toilets have that little hole on the bottom for water to go through. I think that the only hole in the toilet bowl of a gravity-fed rim jet toilet is the hole that waste goes through on its way to the P-trap and to the building drain and then the building sewer. It's my understanding that when a gravity-fed, rim jet toilet is flushed, 100% of the water goes from the tank to the openings under the rim of the toilet, not through a little hole in the bottom of the toilet bowl.

Is my toilet a gravity-fed, siphon-jet toilet?

 

[sevensages]

Update: I cannot tell by looking at the small hole at the bottom of my toilet bowl to determine if water runs through that small hole when the toilet is flushed because there is several inches of water above that small hole. To test whether or not water runs through the small hole (the hole on the left in the photograph in the OP) when the toilet is flushed, I stuck my hand into the toilet bowl and put my fingers about an inch from the outlet of the small hole, and then I flushed the toilet with my other hand. I did feel a strong water pressure of water going out of the small hole in my toilet bowl when I flushed my toilet.

 

[renormalize]

Is my toilet a gravity-fed, siphon-jet toilet?

Your toilet definitely appears to be siphonic:

(from https://www.chinalory.com/Siphonic-vs-Washdown-Toilet-Which-Flushing-System-Is-Better.html)

 

[sevensages]

Your toilet definitely appears to be siphonic:
View attachment 365597
View attachment 365598
(from https://www.chinalory.com/Siphonic-vs-Washdown-Toilet-Which-Flushing-System-Is-Better.html)

renormalize, thank you for your response. Can I get a second opinion and a third opinion here? Does everyone agree with renormalize that my toilet is a gravity-fed, siphon-jet toilet?

 

[256bits]

Toilet terminology.
Who comes up with this stuff?
I would call a gravity fed toilet the outhouse.
And the others just variants of the main style syphon.

Most toilets one sees and uses are just deviations from the physical concept of the syphon.
But I guess everything has to be overcategorized for confusion.

This, I believe, is a variant of the gravity-fed, siphon-jet toilet
But don'r hold me to it due to the silly terminology the manufacturers and industry has come up with.
( ie. without the front little hole, would the toilet become the simple gravity-fed, rim-jet? Or is gravity-fed, rim-jet the variant one with a jet ( larger than the rim swirl jets ) coming out of the top front just under the rim ? )

https://architizer.com/blog/practice/details/how-to-specify-toilets/