A conveyor oven has several heating zones. Each heating zone is comprised of one or more infrared emitters that are configured to emit a spectrum of infrared wavelengths that varies in intensity and spectrum over time. The spectra of emitted infrared wavelengths in each zone can have the same or different profile. Zones are regions wherein infrared emitters are configured and operated to emit the same or substantially the same infrared energy wavelengths and intensity levels across an IR spectrum. Access to the infrared emitters and the conveyor is provided by one or more access or maintenance ports formed into a side of the conveyor oven. Temperature control inside the oven is effectuated by venting hot air through air vents formed into the oven sides and/or top.