My boiler lets me set the hold temp at 208f(97.8C), 195F(90.5C), and 175F(79.4C). So basically you can do all the different "ideal" temps depending on which tea you make the most.

We keep it at 195 since we don't make black teas, and then we can let it cool down to whichever tea we want or just mix it with some filtered cold to get it to temp.