Valve authority is a dimensionless parameter that represents the valve’s ability to control flow in a hydronic system. It is defined as the ratio of the valve’s flow coefficient to the system’s flow coefficient. A valve with high authority can effectively control flow, while a valve with low authority may not be able to maintain the desired flow rate. In hydronic systems, valve authority is critical because it affects the system’s stability, controllability, and overall performance. A valve with adequate authority ensures that the system operates within the desired parameters, while a valve with inadequate authority can lead to system instability and poor performance.