Hi Inuart88,
I have a very small tent I Think it's 2 by 2.5 so far it is working for me, but it seems that I am always thinking and adjusting everything about my grow, including the Heat and Humidity.
So this is what I have found out so far and today that may change, now remember this is in my small tent.
In my small tent I have 2 300w led lights, plus 2 cfl's. I can almost get away with not having a fan or humidifier in my setup. Depending how close ( in the early stages of plant life, Led was close) and 2 cfl's were also close, the temp would get up to 85 degrees, and humidity was 30 or lower, turning on the 2nd led, Adding the 2nd led was not an option.
So I read some more and find out for young plants-- 85 degrees 30% rh, was at the max for high temp and low humidity. Not really knowing what would work I bought a small 10 inch fan and a Vicks humidifier. After installing and adjusting the fan speed (3 speed fan) and Humidifier (high or low) with 1 led and 2 cfl's I can pretty much maintain 77 - 80 degrees and 42-52 rh and since adding the fan and controlling the humidity my young girls have really taken off. What affects the temp and humidity now is that during the day the sunlight come into my tent room and so the tent room and then the tent will warm up a bit.
Now that girls (Northen Light auto's) are about a month old I am trying to give them as much light as possible, It is one big experiment, a couple of times a day I will check the temp and rh, and this is what and where I am today. -- The led lights, (from the manufacturer should be 18 -30 inches away) Adjusting that height also will increase and decrease my temp and rh and I am at a happy medium with that. I am now adding the 2nd led light, for that I wait until the sun goes down, I adjust it a bit higher above the plants that the other led and leave that on overnight. The temp usually gets to 81 and humidity drops to 42, so far my 2 girls seem happy with that and so am I.
So for my first grow and responding to this topic, my point is this: You have to take the great information here, apply it to your personal grow and your environment. Finally, you have to love experimenting with your grow as much as growing, if that makes sense?