Andy in Germany
Guru
- Location
- Rottenburg am Neckar
The element can get too hot, and the thermostat, often reliant on steam from the boiled water to activate it, can burn out. Leaving the kettle boiling that bit longer each time.
Assuming yours is a stovetop kettle, it's steam that provides the whistle power. Emptying it fully, from boiling, allows a "scale" to build up when you leave it back down empty. In effect, burning it slowly.
The "burning" is common to any type of kettle, and will in time lead to an early failure.
That's why I use the pasta sauce Jar and not my mug- it means there's a bit more water in there to stop things getting bunged up.