Heater Core Mounting

I've noticed in most designs/installs that peeps are mounting the heater core in an upright position with the barbs at the top. I'm wondering, does it make if a difference? Suppose I want to mount the heater core on it's side will it still perform good?

In a vehicle the heater core is typically under a constant pressure and it really doesn't matter too much about the position of the core.

it matters not the orientation that you have your heatercore. mine is laying on its back in the top of my case... just so long as you have it positioned to draw in cool air with a fan you're set

I like having the barbs in an upper position. It makes it easier to bleed. Once the system is filled an properly bled, the orientation doesn't make a difference.