An aquastat is primarily sensitive to changes in what?

An aquastat is a device specifically designed to monitor and regulate water temperature within a system, such as a boiler or a heating system. It functions by detecting the temperature of the water and controlling the operation of the heating elements based on that temperature reading. When the water temperature rises above a preset level, the aquastat can signal the heating system to turn off, preventing overheating. Conversely, if the temperature falls below a certain point, it can activate the heating system to maintain the desired temperature.

This specialized function is why the correct answer is related to water temperature. The other options focus on different parameters that do not pertain to the primary purpose of an aquastat. Water pressure, water level, and water quality are important in various systems but are not the key focus of an aquastat's operation, which is exclusively temperature control.