What is the primary function of a thermal expansion tank in a plumbing system?

The primary function of a thermal expansion tank in a plumbing system is to absorb excess pressure caused by heated water expansion. When water is heated, it expands, which can lead to an increase in pressure within the plumbing system. This excessive pressure can potentially damage pipes, fittings, and appliances. The thermal expansion tank serves as a buffer, allowing the expanded water to flow into the tank, thus relieving pressure in the system and preventing any undesirable or dangerous outcomes.

The construction of a thermal expansion tank typically includes a bladder or diaphragm that separates the air and water, allowing for the safe absorption of pressure variations while maintaining system balance. This function is crucial in closed systems, where water cannot escape freely, making the thermal expansion tank an essential component for maintaining safety and efficiency in plumbing systems.