Autoclaves with combined airflow to provide controllable heating or cooling of parts being processed are disclosed. Gas flow along the autoclave is provided in one or more duct areas (48,52), with a plurality of duct valves (50) along the duct (48,52) controllably diverting the gas into the working area of the autoclave. In a fully configured autoclave, duct valves (50) divert gas flowing from the fan or blower (38) from the ceiling, sides and floor of an autoclave to provide a controllable, three dimensional, air flow in the working area of the autoclave. Control of the duct valves (50) may be manual or automatic, with individual or ganged duct valve control. Computer control based on temperature sensor on parts in the working area of the autoclave may be used to provide uniform heating or cooling, or intentional non-uniform heating or cooling rates. Various embodiments are disclosed.