Guys, I'm a mid size miner (i Have 250 rigs) I also own a HVAC company. I have survived 3 years of Texas summers where ambient is 105. The key and I can not stress this enough is ventilation. The more the better. Don't be stupid and add 1 box fan for 10 units on the window. Buy a 3000 cfm or bigger unit. Put it this way, I have 30 units in one location that is 130 square feet and air-flowing from attic and pumping out through window at a rate of 9000 cfm. Its a vortex in there to battle the Texas heat. Is cooling it better? Absolutely but the cost incurred is great, plus it takes 50 amps of mining away.
dagarair: Thanks for the post, good stuff. I'm curious what your thoughts are on airflow for a home "server room" in the Midwest (Northern Illinois). Based on my prelim calculations, I probably won't need AC ever (middle of summer is iffy) to cool the room however I'm designing it now and my main concern is a large enough exhaust. Since I have to open up my exterior wall (twice, for intake/exhaust), I'm trying not to make holes bigger than the width of the studs. The room will have dimensions of 4' by 13.5' (54 sq ft). My hot aisle airflow isn't ideal however it's not terrible either. It will be semi-sealed with only an exhaust fan and (industrial grade?) filters on the intake (don't want critters/dust/etc in my server room). I also need to manage the sound since I live in a residential area and my neighbor is 15' from the edge of my house... I'd considered looking into exhaust designs to minimize the sound so all my neighbors don't hear it all day...
Any suggestions on an exhaust fan (CFM rating)? I'm not asking you to endorse a specific product however I'm not opposed to some suggestions either.
I almost forgot, my current design for that room will be generating 90k btu/Hr. I'm working on a secondary room design that'll generate another 120k btu/Hr of heat, same question there and would love a suggestion on exhaust fan capacity.
I realize this is subjective since what one might feel is an adequately cool room will differ but it gives me somewhere to start.