AGA traditional heat-storage cooker: roasting oven not reaching normal temperature; food takes much longer to cook.

Safety first: For gas or oil-fired AGA cookers, turn off the fuel supply before inspection. For electric AGA modules, isolate at the mains. Surfaces may remain hot for many hours; use heat-resistant gloves.

• Check lids and doors: Ensure the oven door closes firmly and the lid seals are intact. Replace worn rope seals or door gaskets to reduce heat loss.
• Verify thermostat setting: On electric AGA modules, confirm the control is set to the correct temperature or mode. Avoid running in economy/low mode when full temperature is required.
• Measure internal temperature: Use an oven thermometer to check actual cavity temperature. Compare with expected AGA roasting oven temperature.
• Inspect elements (electric AGA): With power off, access the element housings and test each element for continuity. Replace any open or significantly high-resistance elements.
• Check burner/flue (gas/oil AGA): Ensure the burner is clean and correctly adjusted, and that the flue damper is set per AGA instructions. Poor combustion or incorrect flue setting can reduce oven temperature.
• Insulation assessment: If the cooker is very old and loses heat quickly, internal insulation may be degraded. This is a major job and should be handled by an AGA specialist.