Which component absorbs water volume changes due to heating?

The component that absorbs water volume changes due to heating is the expansion tank. When water is heated, it expands, and as a result, the volume increases. An expansion tank provides a space for this extra water to go, which helps to prevent excessive pressure build-up in the system. This is particularly important in closed-loop systems where water is continuously circulated. The tank accommodates the increased volume by allowing water to flow into it, keeping the pressure within safe limits and ensuring the system operates efficiently.

On the other hand, a pressure gauge simply measures the pressure in the system but does not deal with volume changes. A valve controls the flow of water but does not provide any allowance for volume expansion. Meanwhile, a pump is responsible for moving water through the system rather than addressing changes in volume due to heating. Therefore, the expansion tank is the critical component designed specifically to handle the fluctuations in water volume resulting from thermal expansion.