An oven for heating tubular parisons to a target or orientation temperature. A first plenum on one side of the oven and a second plenum on the opposite side of the oven, both exhaust to a common chamber disposed therebetween. The parisons are heated by a high velocity fluid above the target temperature in the zone defined by the first plenum and the chamber and the parisons are tempered by a lower velocity fluid at the target temperature in the zone defined by the second plenum and the chamber.