When selecting valves for a hydronic system, it’s essential to consider factors such as flow rate, pressure drop, valve authority, and valve rangeability. Valve authority, which is the ratio of valve flow coefficient to system flow coefficient, affects the valve’s ability to control flow. Rangeability, which is the ratio of maximum to minimum flow rates, determines the valve’s turndown capability. Additionally, the valve’s materials, actuation method, and control signal type must be compatible with the system’s requirements and operating conditions.