Water jacket stove and thermosiphoning

I’ve read about those Chofu stoves for heating hot tubs where the water surrounds the firebox. Iam wondering is there pipe between the sides where the water is or is there just a low inlet and a high outlet? Would thermosiphoning work like that??

I understand the topic but not your question.
Can you include an image

Here is a pic of stove with inlet and outlet. Iam assuming the two ports are just welded to outside jacket. Other water heaters people made up consist of tubing wrapped (outside)or coiled on inside of stoves. So water heats up creating a suction within the pipe  but the stove in the pic has no pipe so I wonder the the suction process work the same way or is there pipes within the walls since it has an inner wall and outer wall with water in between?