The load controller is a fairly simple controller, using a PID controller to determine the load. The controller has a predetermined set-point for the pressure in the steam dome. The measured pressure is used to determine the error, which in turn is fed to the PID controller. The output from this controller is limited to the interval 2-10 V, representing a percentage interval of 20-100 %. The signal is limited to a minimum of 20 % so that the combus- tion is maintained, since if the load where to be 0 % the combustion would need to be manually started every time the demand rises. This value is then sent to the air and fuel controllers. Figure 5.4 shows the block diagram for the load controller.