An oven with a heat recovery system to recycle waste treatment air used to treat a product in process in a downstream oven zone configured to create a preheating air to preheat the product in process in a preheating zone prior to entering the downstream oven zone, comprising: an oven having at least one oven zone configured to treat a product in process and including a zone inlet for the introduction of a treatment air having a treatment air temperature and treatment air dew point temperature for treating the product in process and a zone outlet for exhausting the waste treatment air following the treatment of the product in process; - a preheating zone disposed upstream of said oven configured to preheat the product in process prior to entering the at least one oven zone and including a preheating inlet for the introduction of preheating air having a preheating air temperature and a preheating air dew point temperature for preheating the product in process; characterized in that it comprises an oven duct assembly extending from said zone outlet configured to exhaust the waste treatment air following the treatment of the product in process; and - a transfer duct extending between said oven duct assembly and said preheating zone configured to transfer at least a portion of waste treatment air from said oven duct assembly to said preheating zone configured to create the preheating air to preheat additional product in process; wherein the oven is configured such that the preheating air preheats the product in process in the preheating zone to a product temperature being at least equal to the treatment air dew point temperature for eliminating surface condensation on the product in process during treatment in said oven zone; said oven duct assembly extends from said zone outlet to said zone inlet configured to exhaust the waste treatment air following the treatment of the product in process, and wherein at least a portion of the waste treatment air is conditioned in said oven duct assembly for creating new treatment air to treat additional product in process; and further including an oven duct regulator configured to control the flows of the treatment air, the waste treatment air and an ambient air, through, into and out said oven duct assembly. an oven having at least one oven zone configured to treat a product in process and including a zone inlet for the introduction of a treatment air having a treatment air temperature and treatment air dew point temperature for treating the product in process and a zone outlet for exhausting the waste treatment air following the treatment of the product in process; - a preheating zone disposed upstream of said oven configured to preheat the product in process prior to entering the at least one oven zone and including a preheating inlet for the introduction of preheating air having a preheating air temperature and a preheating air dew point temperature for preheating the product in process; characterized in that it comprises - a preheating zone disposed upstream of said oven configured to preheat the product in process prior to entering the at least one oven zone and including a preheating inlet for the introduction of preheating air having a preheating air temperature and a preheating air dew point temperature for preheating the product in process; an oven duct assembly extending from said zone outlet configured to exhaust the waste treatment air following the treatment of the product in process; and - a transfer duct extending between said oven duct assembly and said preheating zone configured to transfer at least a portion of waste treatment air from said oven duct assembly to said preheating zone configured to create the preheating air to preheat additional product in process; wherein the oven is configured such that the preheating air preheats the product in process in the preheating zone to a product temperature being at least equal to the treatment air dew point temperature for eliminating surface condensation on the product in process during treatment in said oven zone; said oven duct assembly extends from said zone outlet to said zone inlet configured to exhaust the waste treatment air following the treatment of the product in process, and wherein at least a portion of the waste treatment air is conditioned in said oven duct assembly for creating new treatment air to treat additional product in process; and further including an oven duct regulator configured to control the flows of the treatment air, the waste treatment air and an ambient air, through, into and out said oven duct assembly. - a transfer duct extending between said oven duct assembly and said preheating zone configured to transfer at least a portion of waste treatment air from said oven duct assembly to said preheating zone configured to create the preheating air to preheat additional product in process;