Caleffi’s iSolar MX LTE is a powerful multifunctional temperature differential controller with add-on system functions for use in a wide variety of solar-thermal heating applications. The MX LTE is equipped with five relay outputs and one 0-10 V pump speed control signal output for high-efficiency pumps. The 20 predefined system arrangements, with additional optional functions, are configured for control of: standard solar water-heating systems, drainback systems, multiple storage tanks (up to four total), heat dump and storage-tank booster heating.