I'd like more info on cob heaters, too, but with metal 'innards' like a draft-controlled firebox to direct heat to a cooktop & oven. Could this be done? The thermal mass & safety of a cob exterior, combined with the utility of an old fashioned cookstove..... I wonder how the cob would hold up. Would the iron change sizes with heating/cooling, crumbling the cob. If anyone's tried this please let me know. Joy