I live in a very hard water area and can't keep on top of the limescale that kills my electric kettles. I'm thinking of buying a stove top, would that suffer the same fate?
Maydup, I found them to be very expensive, too - and I don't think the filters are environmentally friendly either although I did recycle them at Tesco.
I haven't got room for a water softener, sadly.
I grew up in a hard water area with a kettle on the gas with a whistle. When we bought a new electric kettle it was a novelty but we couldnt afford to replace it like we can nowadays. We had to scrub it and descale it with vinegar, and our catchphrase was .... Put the kettle on before it furrs over completely!
These electrical water "Conditioners" not softeners work by changing temporary hardness, which can be removed by boiling and will fur up kettles and so on, to permanent hardness. This doesn't get deposited on the inside of the kettle but will be left behind when water is evaporated, so the water you pour out after the kettle has boiled will have marginally more "hardness" in it than when it came out of the tap. I lived in an area of America with permanently hard water. It makes scummy hot drinks and is horrible to wash with as the soap/shower gel etcet will not lather. https://www.bbc.co.uk/bitesize/guides/z686pbk/revision/1
With respect, nobody has mentioned the easiest, cheapest method of keeping your kettle scale-free.
You can buy from your hardware shop or online wire balls or coils which you pop into your kettle. They are small but they collect almost all the scale. When they are full you just roll them with your fingers under the tap to dislodge the scale and they are ready to go again. They cost a couple of quid and last forever.