I see you are pushing the hot air out the window.. where is the cool inlet air coming from? If this is an inclosed garage, wouldnt this cause negative air pressure? Reason I ask is Im thinking about doing this in my garage since I cant find a good hosting company for my S9s. Thanks!
It would be too hot to run in my garage, it's in a bedroom. The cool air is being generated via a portable AC, with the intake hose outside of the room pulling in air from the rest of the house.
If you're going to run in your garage, just make sure it's not too hot and that you have good airflow (intake & exhaust).
With 18 L3s you need around 4,000 cfm (18*220cfm) on your "cool room" how much air is your portable AC providing? Same on the "hot room" Be careful with positive and negative pressures.