While the element is on the resistance will be just about constant, as it is significantly hotter (internally where the resistive part is) than the water. When it is off, the resistance should be quite a bit lower (resistance increase with temp).
I'm guessing that the kilowatt rating is rated when submersed in water, and the resistance will only change slightly with variations in water temperature.
e.g. with P = V^2/R, a 3kW element is about 17.6 ohms with V=230V. If that resistance were to change to 17ohms, the power rating would be 3.1kW. I reckon that in reality the resistance might only change by 0.1ohms depending on the water temperature.
I'm guessing that the kilowatt rating is rated when submersed in water, and the resistance will only change slightly with variations in water temperature.
e.g. with P = V^2/R, a 3kW element is about 17.6 ohms with V=230V. If that resistance were to change to 17ohms, the power rating would be 3.1kW. I reckon that in reality the resistance might only change by 0.1ohms depending on the water temperature.
Comment