How does a sweet-potato machine maintain stable upper and lower heat?

Use separate controls for upper and lower zones or position sensors properly to keep temperature variation within design limits. One sensor may allow hot spots or uneven cooking. Checklist: Define capacity, accuracy, materials and operating environment before requesting quotes on a uniform basis. Request specification sheets, test reports, certificates, maintenance manuals and spare-part lists. During acceptance, verify appearance, dimensions, functions, safety protection and packaging, and keep test records. Do not compare unit price alone; include customization, freight, spare parts, after-sales support and downtime risk. Keep written records of inquiries, confirmations, FAT, acceptance and warranty commitments.