Red Seal Plumbing Practice Exam

What device compensates for the normal expansion and contraction of the water in a hot water boiler?

1. Pressure relief valve

2. Diaphragm tank (expansion tank)

3. Low water cut-off

4. Limit control

The correct answer is: Diaphragm tank (expansion tank)

The expansion and contraction of water in a hot water boiler can increase and decrease the overall volume of water, potentially causing pressure changes and damage to the boiler. A pressure relief valve is designed to release pressure in case of emergency situations, such as high pressure levels, but it does not specifically address the normal expansion and contraction of water. A low water cut-off is responsible for monitoring the water level in the boiler, but it also does not address the issue of water expansion. A limit control is used to regulate the temperature in the boiler and does not compensate for water expansion. The diaphragm tank, also known as an expansion tank, is specifically designed to absorb the expansion and contraction of water, preventing pressure changes in the boiler and ensuring its safety and efficient operation. Therefore, the diaphragm tank is the correct answer.