Which of the following controls should be employed in a heat drying system?

Maintaining acceptable temperature limits, avoiding heat spiking, and preventing overheating are crucial controls in a heat drying system for several reasons. Firstly, excessive temperatures can damage materials being dried and can lead to thermal degradation, negatively affecting their structural integrity and performance. Additionally, heat spiking can create uneven drying conditions, which might lead to warping or cracking in sensitive materials. Proper temperature control ensures that the drying process is efficient while also protecting the quality of the materials involved, facilitating a more uniform and effective drying outcome.

By avoiding conditions that could allow for overheating, operators can also prevent potential hazards, such as combustion or toxic fumes given off by certain materials when subjected to excessive heat. This approach also contributes to energy efficiency, as maintaining a regulated temperature typically utilizes less energy compared to constantly having to readjust systems due to overheating issues.

In contrast, employing the other strategies outlined in the remaining options could compromise the efficiency and safety of the drying process.