| 摘要 |
PURPOSE:To prevent a heat exchanger from becoming an abnormal high temperature and permit to realize a highly reliable device by a constitution wherein water is poured automatically until water level, capable of effecting additional heating, is achieved, thereafter, an additional heating means is ignited, in case the water level is decided by a water level deciding means that the additional heating can not be effected in that water level. CONSTITUTION:The water level detecting means 14 employs a pressure sensor 15 and operates the water level by measuring air pressures in an air trap 17 and a tube 16, which are varied in accordance with the water level in a bathtub 2. A water level signal (a), outputted from the water level detecting means 14, is compared with an additional heating control water level VMIN, outputted from an additional heating water level setting means 19, in a comparison means 20 to output a water level deciding signal (b). An additional heating cnontrol circuit 7 is provided with a function to operate the additional heating means 1 when the water level in the bathtub 2 is higher than the allowable level of additional heating and a hot-water pouring control circuit 9 is provided with a function to operate the hot-water pouring means 8 when the water level in the bathtub 2 is lower than the allowable water level of additional heating, whereby there may be no danger to blow boiled hot steam out of a water flowing pipe. |
