Heat can come from an internal heating element, external hot water, or both systems. Some washers use the available temperature and do not include a heater.
How energy reaches the tub
An internal heating element converts electrical energy into heat within the intended circuit. With a hot-water supply, part of the energy has already been used up before the water reaches the machine. Dual-inlet models can mix supplies according to their valves and the cycle.
The cold and hot water connection must match the design. Connecting hot water to an unauthorized inlet can change washing conditions and components; it is not a universal way to save electricity.
What the thermal sensor does
The sensor reports temperature at its measurement point. The control system decides when to heat or mix, subject to conditions such as level, phase, and safety limits. A thermostat or limiter may provide another function, but not all appliances use the same parts.
The selected temperature does not necessarily describe the entire curve: it may be a reference, a maximum, or part of the program profile. Heating and rinsing can happen under different conditions. Touching the glass when the cycle ends does not measure what happened during the wash.
How to read consumption and behavior
When calculating energy per cycle, separate electricity used by the appliance from energy supplied by external hot water. The steam function is also not the same as keeping the entire tub hot.
If the temperature seems wrong, start by identifying the system and the cycle. Checking a heating element requires a different level of diagnosis and documentation.
To interpret a temperature, identify its source, the measurement point, and the phase it belongs to.