Patent ID: 7028768

Claim:
A method of controlling a hydronic system, the hydronic system including a plurality of fluid heat exchange units for feeding a load, and a bypass valve for bypassing fluid flow from the load, the method comprising the steps of: operating at least a first and a second fluid heat exchange unit in the hydronic system to heat or cool a fluid; monitoring an output fluid flow of each of the operating fluid heat exchange units; comparing the monitored output fluid flow to a predetermined fluid flow setpoint; adjusting the output fluid flow of each of the operating fluid heat exchange units towards the predetermined fluid flow setpoint if the monitored output flow is different from the predetermined fluid flow setpoint by at least a predetermined margin; monitoring a combined output fluid flow of the operating fluid heat exchange units; at least partially opening the bypass valve if the combined output fluid flow is below a predetermined minimum combined output fluid flow; and operating a previously idle fluid heat exchange unit if the combined output fluid flow is greater than a predetermined maximum combined output fluid flow for the number of operating fluid heat exchange units.