Tekmar Mixing Control (Variable Speed). Mixing Control 356 is designed to operate a mixing pump to control temperature in a hot water heating system using Outdoor Temperature Reset. It can be used in applications ranging from in-floor radiant to commercial baseboard systems for boiler protection with full reset. This control regulates a single heating water temperature through Outdoor Temperature Reset. It provides mixing by speeding up or slowing down a single permanent capacitor (standard wet rotor) circulator.