Note the opening to the left of the tank, exhaust gases travel counter clockwise around the tank once the insulated top is installed
Two water connections to the tank, hot through the upper pipe, cold through the pipe that exits the enclosure botom
I prefer to think of the junk you see as a parts depository, the stove pipe comes up in the center of a poured concrete 2′ wall from the basement, runs horizontally, then down to the ground
The wider area of the pipe after the angle pointing down houses a small fan,
Though it looks solid from the sides, there is actually quite a wide openiong for the exhaust to exit. This configuration keeps the fan dry, allows for a small amount of falling for the exhaust as it cools, and protects pretty well against strong wind
sThe tank enclosure has an insulated top and sides, with just enough room to circulate exhaust around and over the tank to transfer as much heat as possible to the water.