You’re unlikely to find any device designed to keep water boiling possibly because it’s inefficient and there’s danger of boiling over or applying high heat after the water has boiled into steam.

Although this blog post mentions the use of boiling water for black tea, keep in mind these things:

- All you need is sufficient temperature for “full infusion”. (“Sufficient” of course being left vaguely defined by most tea drinkers, mildly irritating the scientist in me.)

- Boiling temperature varies with atmospheric pressure (in most cases, primarily altitude) and require impure water. (Absolutely pure water will not boil until some impurity is added–such as a dust, a pinch of salt, or a spoon–and thus is very dangerous)

- On a less scientific (more opinionated) front, I’ve been advised by people who’s tea I’ve complimented that the water should never be boiled, but should be near boiling.

And now we’re back to slightly vague term “boiling”…which with typical water at sea level would be about 212 degrees Fahrenheit. The customer’s quoted 200 degrees is only 6% less than that and should suffice (assuming she meant Fahrenheit, since 200 degrees Celsius would be quite unusual and dangerous to say the least).

The advice to soak or swirl some of the hot water in the cup to preheat the cup is good, though. You might also add “steaming the tea bag for a minute or too before getting it wet” to the list of steps for perfect tea, but I’m not yet convinced how much difference this makes.

Aeration should not be a problem. Just hold your pot lower and make sure the water is hitting the water in the pot, thus splashing and aerating, instead of hitting the side of the pot.

Most countertop units keep the water hot but not boiling. However, they also have a boil/reboil function to bring it back to boiling temperature.

Use Brita filtered water to fill the countertop unit.

Also, for proper tea brewing, one should always preheat the pot and cups and rinse the tea.