Nice. I am the opposite for my winter indoor grows...I try to maximize heat retention because I grow in a 50-60F space.Yes, the LED's warm up the air in the drum, I lower the temp in the drum by blowing colder air into the drum, more air = colder, less air = warmer.
I am at week 5 now and in soil it takes 6 - 9 weeks, in hydro it takes about 4 weeks according the Internet so I am behind to the latter. I might have lost one week because of my clumsiness in the beginning and probably I could fine-tune things a bit but as it looks I might beat soil in the future but not DWC hydro, at least not with lettuce....? What is the normal grow time for the lettuce, has your system sped up this process ?