Why does a commercial oven heat slowly?

Please verify the following points and require itemized written supplier responses:（commercial oven oven-slow-heating） Common causes include low voltage, low gas pressure, damaged elements, leaking seals, overloading or faulty fans. Check energy supply and seals, then inspect heating parts before continuing full-load operation. 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.