Abstract: An annealing lehr comprised of a plurality of serially arranged heating and cooling sections which form a continuous treating chamber through which the ware passes during the annealing operation. An endless foraminous conveyor belt moves through the treating chamber and supports the ware to be annealed, with both the charging and return flights of the belt being located within the heating section to pre-heat the return flight. At least one burner is mounted adjacent the top and at each side of each heating section, and the burners fire directly into a duct which communicates with the inlet of a fan positioned centrally above the treating chamber. The circulating system includes down ducts at each side of the treating chamber and electrical heating elements can be located in the down ducts for providing the necessary heating, in lieu of the gas burners.