Red Seal Oil Heat System Technician Practice Exam

What is the purpose of a thermal expansion tank?

1. To increase the overall heating system capacity

2. To absorb excess pressure changes in hot water systems

3. To provide additional hot water when needed

4. To filter out impurities from the water

The correct answer is: To absorb excess pressure changes in hot water systems

A thermal expansion tank is specifically designed to absorb excess pressure changes in hot water systems. As water is heated, it expands, which increases the pressure within the closed loop system of a water heating system. Without an expansion tank, this increase in pressure can lead to stress on pipes, fittings, and appliances, potentially resulting in leaks or failures. The expansion tank provides a space for this extra volume of water to go, helping to maintain a balanced pressure in the system. This not only protects the integrity of the system but also contributes to the efficient operation of the water heating system. The other options do not accurately describe the primary function of a thermal expansion tank. While the capacity of the heating system is important, the tank does not enhance it directly. Additionally, while supplementary hot water storage may be a feature of certain systems, it is not the role of the thermal expansion tank. Lastly, filtering impurities from water is handled by different components within the system, such as filters or water treatment systems rather than the expansion tank itself.