The ECL Apex 20 is used in large district heating applications. The product is designed and produced by the company Saia-Burgess. The ECL Apex 20 is a free programmable controller (FPC / PLC) for temperature and pressure control as well as monitoring of district heating systems. The ECL Apex 20 is operated by means of a PC. Temperature input signals are based on Pt 1000 or 0 - 10 V. Pressure input signals are based on 0 - 10 V. Activation of the motorized control valves is based on 0 - 10 V signals. Activation of the pumps is based on relay outputs. The advantages of the ECL Apex 20 are among others: free programmable controller , flexible input and output configuration and extension, flexible communication possibilities, onboard web server. The ECL Apex 20 is to be placed inside a panel.