The thermal resistance of the thermal resistance of the electric heater, the thermal resistance is mounted near the electric heater outlet, and the temperature of the temperature is the highest temperature (heat element surface temperature) of the temperature (thermal element surface temperature).

The internal supernatal alarm is to prevent it from being set due to the high temperature of the electric failure such as a heat generating element, if the electric heater is working properly, the temperature should be close or slightly higher than the electric heater indoor heater outlet temperature.(Several to dozens of degrees, this can be obtained with several other electric heater operations), E-404 outlet temperature control 120 ° C, internal over-temperature alarm temperature setting increased to 300 ° C, still over temperature alarm problem,Moreover, after the heater stops heating, the temperature can still gradually fall, indicating whether the temperature measurement is correct, but the thermal resistance is problematic, and the electric heating tube cannot be opened because the inspection cannot be opened in the operating state, so it cannot be confirmed.