Need a picture of the tank.

Copper tanks for heating water on top of a kitchen store were common equipment in homes dating up to 1940. Also, many coal or wood fired kitchen ranges had a copper tank in the end of the stove opposite of the firebox, maybe 5 gal in size. it was used as a source of hot water for the kitchen.

Copper tanks were used for immersing jars in hot water during the canning process.