I had a '99 Acura TL that had a heated intake system. I'm not sure why, exactly, but it had a "mini-radiator" with a vacuum actuated door that diverted intake air over a coolant-heated device. My guess is that it heated the air on cold starts to improve emissions. To remove it (if you wanted) required a tie of the high-pressure coolant lines, or leakage would result. I haven't seen that on anything other vehicle, first hand.
I experimented by forcing the door open for a modified warm-air intake. On this particular vehicle, some malfunctioning sensors prevented an accurate test.
RH77