When do heat-drying systems perform at their best?

Heat-drying systems perform optimally when outside air is cooler and drier than inside air. This condition is crucial because cooler, drier air is more capable of absorbing moisture, enabling the drying process to be more effective. When air from the outside enters the drying environment, it can lower the overall indoor humidity, allowing for increased evaporation of moisture from wet materials.

In this scenario, the heat provided by the drying system enhances the ability of the air to hold more moisture, thereby accelerating the drying process. The combination of lower humidity levels outside and the additional heat creates an ideal condition for moisture removal, maximizing the efficiency of the drying system.

The other options do not provide the same advantages. If the inside air is warmer and more humid than the outside air, it may impede drying. When both air masses have equal moisture levels, there is no driving force for moisture to leave the materials being dried. Maintaining indoor temperatures below 60°F can slow down the drying process, as lower temperatures generally hinder evaporation.