Do you have multiple miners?
If not, wouldn't hanging them horizontally do the same thing? (Assuming you're not touching a heat resistant surface)
It's lacking a few thing's that I see. We really could use info like what miner's he's running and number of miner's. As different miner's could be a huge difference in watt's used and heat.
A picture of setup and further specifications would let us know a lot more. I personally have always positioned miners horizontally never have had the need to try vertical setup. With my mining area horizontal works just fine no performance issue's. I do use a decent amount of CFM's though during midwest heat during summer to keep gear cool. So vertical setup.... very much depends on your setup. Have not seen a decent sized mining area use vertical setup that I can think of though.