From my tests, 260c with an f3 preheat get's the hottest. I tested at 260c at f2 and 260c at f1 and the elbow got the hottest at f3.
With the fan off, the top of the elbow is cool to the touch even at 260c. At fan 3 the top of the elbow gets too hot to touch.
I'm thinking an f3 preheat is a...