Red Seal Plumbing Practice Exam

An aquastat on a hot water system will open when:

1. Low minimum temperature is reached

2. High maximum temperature is reached

3. There is a loss of pressure

4. Water flow decreases

The correct answer is: High maximum temperature is reached

An aquastat is a device that controls the temperature of a hot water system. It is typically set to a specific high maximum temperature, and when that temperature is reached, the aquastat will open the circuit and shut off the heat source. This helps prevent the water from overheating and potentially causing damage to the system. The other options (A, C, and D) are incorrect because they do not pertain to the function of an aquastat. While it is possible for an aquastat to also have a low minimum temperature setting, it is not the typical function of the device. A loss of pressure would not affect the temperature control of a hot water system, and water flow decreasing is a sign of an issue with the circulation of water rather than the temperature. These options can therefore be ruled out as potential answers.