Heat meters are devices used to measure the energy consumed in heating and cooling systems. Central system installation structure is used in collector (mobile) systems. The heat meter calculates the difference (t) by measuring the inlet and return line temperatures with its double sensor. It also measures the amount of water (m3 / h) passing through the installation with a flow meter. Energy calorimeters show all measured values (flow temperature, return temperature, flow rate) as well as consumption values on their screen and send them to the communication unit. It also stores these values in its memory.