It enables the simultaneous control of the room temperature and the heating medium in an underfloor heating system. It consists of a concealed cassette with a thermostatic valve and a RTL heating medium temperature limiter valve. The RTL head is mounted on the RTL valve, while the thermostatic head of the Brillant or Diamant series is mounted on the thermostatic valve. The valve thermostat responds to changes in the air temperature in the room, while the RTL temperature limiter responds to changes in the temperature of the heating medium in the installation. The thermostatic valve has two connections with external thread G3 / 4 adapted to compression fittings available in the Schlosser range (PEX 16x2. Or Cu 15x2). The valve has an air vent for manual bleeding. The concealed cassette is closed from the front with a front mask.