steam boiler (left side only)
罐 centers on a container for heating or boiling, specifically a steam boiler. The meaning is narrow and technical, referring to a vessel that holds water and produces steam.
罐 combines 缶 (a jar or pot) with 雚, which likely contributes a phonetic element. The character is used for a boiler or kettle, fitting the container sense of 缶.
The left side 缶 is a pot or can, and the right side 雚 looks like a complex arrangement of grass and a bird. Imagine a metal pot (缶) with a lid and spout, like a steam boiler, with steam rising through the grass-like top.
For カン, picture a can (缶) that is also a boiler: can -> カン, and the can-shaped boiler heats water to make steam.
stoker; fireman