For the IBM iDataplex air cooling is front to back, just like a normal 1U server. The inlet temperature ranges are 10C to 32C. The recommended range is 18C to 26C, and the ideal is 73.4F or 23C.
Thanks to Matt Archibald for helping me dig this up.
Also, the iDataplex Rack, on its casters is 82.4″ tall.