These heat meters is largely free from defects inherent in the electromagnetic and ultrasonic flowmeters. The operating principle of the mechanical heat meters based on the transformation of translational motion of the fluid flow into rotary motion of the measuring part. Mechanical heat meters consist of a Calculator and mechanical rotary vane or water meters. This is still the cheapest heat meters, but their value must necessarily add value to special filters, which are set before each mechanical heat meters. Disadvantages mechanical heat meters is the impossibility of their use at high water hardness, the presence in it of small particles of scale, rust and scale that clog filters and mechanical flowmeters. For these reasons, almost all of Russia installation of mechanical flow meters is only allowed in apartments, small private homes. In addition, the mechanical flow meters provide the greatest loss of water pressure in comparison with other types of flowmeters. Eddy heat meters operate on the principle of well-known natural phenomenon – the formation of vortices behind an obstacle standing in the way of flow.
Structurally, the eddy heat meters consist of a triangular prisms, vertically mounted in the tube, the measuring electrode was inserted into the pipe further along the fluid flow, and pipe installed outside the permanent magnet. At speeds above a certain environment limit the vortices form a regular track called 'Karman'. Disruptive flow of fluid flowing in the pipe causes pressure fluctuations in the flow measurement which allows us to define the volume flowing through the pipeline fluid.