| 摘要 |
<p>PURPOSE:To make possible to changeover the wattage with only one sheath heater, and contrive to improve the compactness, low cost and specific performance by a method wherein a diode and a wattage changeover switch is provided with a sheath heater in series. CONSTITUTION:A thermal cutout TC is usually closed, a pressure switch PS closes an electric circuit by the water pressure due to the opening of a valve V. When a wattage changeover switch WS is connected with a terminal, (n), a sheath heater H is directly electrified with the same commercial alternating electric current power which is connected to power source terminals N, L, then an apparatus becomes at a large wattage condition. Conversely, when the wattage changeover switch WS is connected with the terminal (d), a diode D is inserted between the sheath heater H and the power source terminal L, the sheath heater H is electrified with half-wave rectified commercial alternating electric current power, then the apparatus becomes at a small wattage condition. The cooling of the diode D is performed by installing of the idode D on the water passage at the inlet side of a tank T, accordingly, the more effective cooling can be performed than the cooling of usual radiating fin.</p> |
