Minnesota Special Engineer Boiler License Practice Exam

What device is required between a hot water boiler and the expansion tank?

1. A pressure relief valve

2. A shut off valve

3. A backflow preventer

4. An expansion valve

The correct answer is: A shut off valve

The requirement for a shut-off valve between a hot water boiler and the expansion tank is based on the necessity for maintenance, isolation of components, and safety protocols. The shut-off valve allows for the isolation of the expansion tank from the boiler. This is critical when maintenance is needed because it ensures that the system can be drained or worked on without the risk of water flowing back into the system or causing pressure issues. In addition, this valve provides a practical means to control the flow of water to the expansion tank. This control is particularly important during inspections, repairs, or if the expansion tank needs to be replaced. While other devices, such as a pressure relief valve, serve specific roles related to safety and pressure management within the boiler system, they do not function to isolate the expansion tank in the manner that a shut-off valve does.