Heat Flow Meter PLECS 1.5 Online Help Heat Flow Meter Purpose Output the measured heat flow. Library Thermal Description The Heat Flow Meter measures the heat flow through the component and provides it as a continuous signal at the output. The direction of a positive heat flow is indicated by the small arrow at one of the thermal ports. The output signal can be made accessible in Simulink with a Continuous Output block or by dragging the component into the dialog box of a Probe block. Dialog Box Probe Signals Measured heat flow The measured heat flow in watts (W).