DYNAMIC-RESPONSE AND TUNING

HVAC control systems can be especially difficult to adjust or tune bec ause She process gain of the control loop varies with a range of varia bles, including the control point. For example, if the air flow rate o ver a hot-water heating coil is cut in half, the ratio of the change i n outlet temperature to the change in valve position, called the gain of the coil, will increase significantly. This phenomenon is common in multizone and variable air volume applications.