PURPOSE: To maintain the temp. of a bath room floor at an adequate value, by providing a controller which stops hot water supply to a water sprinkler nozzle based on a signal from a temp. sensor which detects the floor temp. and provided at the rear side of the floor.

CONSTITUTION: At an adequate position on the rear side 1b of the bath room floor 1a, a temp. sensor 16 which detects the temp. of the floor 1a is provided, while a control device 17 is arranged in a hot and cold water mixing device 10, and a manipulator 15 and the temp. sensor 16 are connected to the controller 17. At using a bath, by adjusting the temp. setter 15a and turning a hot water heater switch 15a ON, a hot water of set temp. is prepared at the mixer 10 or a bath boiler 11 and is fed to a water sprinkler nozzle 6. The hot water sprayed from the nozzle 6 hits an inclined surface 8, expands in fan-shape in a thin filmy state obliquely upward, and spreads all over the water proof pan 1, heats the bath floor surface and at the same time, heats the whole space of the bath room. When, by the signal from the sensor 16, it is detected that the temp. of the floor 1a has reached the preset temp. the controller 17 closes the valve, the temp. of the bath room floor after divestment is maintained at an adequate temp by hot water sprayed through the sprinkling nozzle 6.