During my 18 months stay in rural Western Australia we that these domestic hotwater cyinders with a fire up the center. The wood they burned was called Mali Roots, very dense wood and you only needed a few bits for the days hot water supply. I guess they are banned in the towns.
Edit: Spelt Mallee and refers to a characterisic of certain eucalyptus trees where several main stems grow from a common tuber like root clump. I remember they were very hard to cut with an axe and about 1 foot by 6 inches in size.