Heatsink questions for RepRap

I have been wondering for a while now why the heatsink is mounted so that the fins run horizontally.

If it was rotated 90 degrees, then the top could be blocked off and the airflow out of the bottom would be in the right place for the hot-end blower. This would simplify the airflow design quite a bit I believe.
I realise that the mounting holes on the heat sink are in a different orientation for the aluminium block, but is that the main reason?

Edited 1 time(s). Last edit at 04/15/2015 10:54AM by VortyZA.

Have been discussed before:

[forums.reprap.org]

Erik

Thanks Eric