Hi there. I've good bit of experience with a closed loop system using aircon and dehumidifers. It worked well but it took a lot of tweaking, time and money for me to get it right. Plus it took a lot of power and created a lot of noise. However I was using 5000 watts of HPS lighting over 10 kilowatts of aircon and 500+ watt dehumidier. The temps stayed a perfect 27 degrees and dropped to about 22 at night and humidity was so low that when they were young I increased humidify using a powerful three head mister in a 25litre bucket of water, but as they grew bigger into veg and flower the humidity was about 40-55 tops. A huge amount of water was pulled from that room via the aircon and dehumids. Much easier to run fan extraction if you can. PM me a link to your grow if you want and I'll check it out and give you more advise there.