U still doing this? Get ready to fight some heat without a powerful AC. I'm currently running 1400 watts (with a total pf about 4400 watts. I'm in the process of installing a 18000 BTU ductless A/C. I am also in a garage. I think it's going to work great, and I think I will even have the option of running the room cooler at night for those colorful strains!