A heat exchange system and method for heating outside air provided to a structure are disclosed. The system uses and recovers heat from waste products that are being exhausted from the structure. A heated products source generates heated waste products as a result of combustion. An exhaust duct passes the heated waste products through a heat exchanger before exhaustion from the structure. An intake duct that supplies fresh outside air to the structure also passes through the heat exchanger. The heat exchanger couples the exhaust duct and the intake duct and transfers otherwise unused heat from the waste products to the outside air to increase the overall efficiency of the heated product source.