Aquastats respond to changes in:

Aquastats are devices specifically designed to monitor and respond to changes in water temperature within a heating system. Their primary function is to ensure that the water is maintained at an optimal temperature for efficient operation, often in hot water heating systems, such as boilers or hydronic heating systems. When the water temperature falls below a certain set point, the aquastat activates the heating element to raise the temperature, and conversely, it can shut off the heating element when the water temperature exceeds a specified limit.

In contrast, flue gas temperature, stack temperature, and air temperature are not the primary functions of aquastats. These parameters may relate to the efficiency or safety of combustion processes but do not directly involve the operation of aquastats in regulating water temperature. Therefore, the focus of aquastats on monitoring and responding to water temperature is crucial for the effective management of heating systems.