From what I understand, this is just how things are with the 360.
I wouldn't recommend doing much to limit the airflow around the 360, especially a refurb model. The only thing I can think of to suggest, is something along the lines of an entertainment center that has a door on it, but with an open back end. So long as you keep this a good 2-3 inches from the wall, it shouldn't obstruct airflow greatly, but it will muffle the sound somewhat.
I bought a refurbished(bigger fan)xbox 360 this week and I have no regrets...except for the loud fan. Is there a way to make it less noisy without having the risk of it overheating? Because my Xbox sounds like a hairdryer...
Thanks in advance.