Hi Mette,
Are you building a hive to accommodate Flow Frames, or do you have Flow Hive?
I am confused by your wording, so I am attaching some photos and our manual for you to look at.
In a Flow Hive the bees should enter in one side - through the entrance / front.
And the honey exists on the other side / rear - this is so the honey can flow out, with the least amount of bees flying in the way.
Michael has used a sealed system with the curved tubes and bucket with holes in it, so the bees won’t be able to get in.
If you are harvesting without a cover etc, it is better to not have the exit on the same side as the entrance…
If you have a Flow Hive - this has a tilt built into the hive - this is designed to allow the honey to flow out more easily and quickly. You need to make sure the tilt is facing towards the rear / exit/honey tubes.
As Michael mentioned it doesn’t matter for him, because he has a Flow Super on top of his own brood boxes. He just props up the hive with a tilt when he is harvesting.
Let me know if you need more clarification 
Here is our harvesting guide with a video:
https://www.honeyflow.com/resources/harvesting-checklist/p/197