The adjustable thermostatic mixing valve in “L” configuration, installed in centralized systems for heating or production of hot sanitary water, automatically mixes the water to the desired temperature using hot water from the boiler and the cold water from the water mains, regardless of the supply conditions. The design, with hot water inlet and mixed water outlet on the same axis, allows for easy installation of the device. Setting range 30÷65°C. Inlets with incorporated check valve and filter on female unions.