I haven't made a pen since moving into my new house. My old shop wasn't air conditioned, but the air moved through it well. Here, the air doesn't move well (despite a large ventilator in the rear of the shop), so I'm saving my nickels for a 5 ton unit. I'm looking at $4100 installed, but I'm waiting on the fellow to come across a dented/scratched unit. The orientation of my shop doesn't allow for natural air flow, and our heat index has been ~110F. After being outside in a refinery all day, I really don't care to be in my new shop that I just HAD TO HAVE!!!