Balancing and control valves

A combined balancing and control valve suitable for use in a hydronic system, the valve comprising a chamber enclosing a plug, a seat and an adjustment means for adjusting a separation of the plug and the seat, monitoring means for monitoring a rate of fluid flow across the separation, wherein the adjustment means comprises a motion transformation means operable by an actuator to control a motion of the valve plug, wherein the valve plug provides a favorable change in fluid conductance of the valve for a given change in a position of the actuator, and wherein the actuator is calibrated in increments which correspond to incremental changes in the conductance, wherein the actuator comprises a rod operable on linear motion to actuate the motion transformation means to adjust separation of the plug and seat and an associated calibration means emerging from the chamber having a scale visible outside of the chamber and is operable to limit a maximum separation between the plug and seat which can be created by the actuator, wherein the actuator rod comprises a toothed rack portion, wherein the motion transformation means is a pinion engaging with the toothed rack portion, the pinion being fixed to a cam plate defining a cam guide of a cam mechanism, wherein the cam plate rotates with the pinion to effect movement of a cam follower, the cam mechanism being operable to adjust the separation of the plug and seat, and further comprising a shaft to which the cam follower is fixed, the shaft being fixedly mounted to the plug, wherein as the cam follower follows the cam guide provided in the cam plate axial movement of the shaft occurs thereby adjusting the separation of the plug and seat, and front and rear bearing plates, the shaft being received at opposing ends thereof and having a same diameter where the shaft passes through each of the two bearing plates.