| 摘要 |
PROBLEM TO BE SOLVED: To provide an immersion heater provided with a warning function, and capable of notifying its state of energization. SOLUTION: In this immersion heater 2 to be immersed in water to heat water, a mark 40 for indicating depth to be inserted into water is formed in ink having a thermally color changing property on a surface of a metal pipe 11, in which a heating element 20 is contained.
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