Kettle "keep warm" function

[tell-me-more]

Just bought a kettle with a "keep warm" function that keeps water at 80 degrees ready to boil in an instant. It works very well indeed, but I'd like to know if overall, keeping the water at 80 degrees saves energy or wastes it, compared to letting the water cool and boiling it again from whatever temperature it falls to.

[Homer55]

not too sure, id of thought that it would use more, but im no expert.

[Gnu]

The most energy efficient way is to boil just the amount you need in time for when you need it.

The reason for this is that hot water loses heat to the surroundings, and hotter water loses heat quicker. Keeping water at 80 degrees loses more energy than letting it cool and then re-boiling it, and both methods use more than boiling it in one go.

[rojash]

I could be wrong, but I would have thought that keeping water at a constantly raised temperature would encourage bacterial growth. In any case, it should make really horrible, stale-tasting tea!

[pagey]

It definately would use more energy. If there is more heat inside the kettle there is more heat lost to the surroundings. The energy used for the kettle to be warming the rest of your kitchen will be pretty much equal to the amount of electrical energy used.

People always tell you to switch things off completely (not standby) and not leave things on. But if it is the winter it is OK as the energy you consume with all these appliances offsets against the energy you need to heat your home.

[Zevon]

Also if the water is at 80 degrees tghen more of it wiull evaporate and be lost to the surroundings, this means more water needs to be added and heated to 80 degrees from cold anyway.

If the kettle was perfectly insulated and vacuum sealed then it would not waste energy, but that is never going to happen. Thermodynamics always wins.