Hey
Your plant looks really good. My first question is: your exhaust sucks air from the shade right and that air that enters the shade is from the room? I think that' is how its set up. Heres the problem with the enviroment controller. Your room will accumulate to much heat to fast; in turn, your exhaust will have to be on to often to build up CO2. It does take some time for your CO2 to build up ppm.
I like the idea that your room is air tight. It will keep the smell at least from creeping because of the heat.
About your timers turning on and off to balance the time between your burner and heat/exhaust, your idea would work but the heat will build up about 1 degree a minute in your 4x6 room. The only way you can build up the CO2 is that you have to turn your exhaust off. When the general try to use CO2 they usually have large set ups were the exhaust can be turned off for about one hour. Remember, you may get your ppm up but your plants will only bask in it for a very short time.
So, if I were you, turn on your 1000HPS light and see how much heat it produces in your room for every hour. I think you have the white and black timer with two plug ins that has the ability for 15 min intervals. Take that timer and after one hour, push in a peg for 45mins with no exhaust and 15 mins for exhaust on.
If you can keep it around 26-27 degrees, that sounds good to me. Keep that system like that. But you going to have to account for the gen producing heat.
The next thing I think about is, do u have a co2 monitor? If so that you can really gauge whats up and see if it's worth keeping exhaust off for 45 mins for every hour. If you can keep ppm above 800ppm thats worth keeping the burner.
Remember that your plants have to bask in the PPM for the whole cycle to gain any benefit. Thats the catch with CO2
BTW the room looks good. I like the choice in reflector. Maybe you could suck not from the room but from anther place so that air runs through the shade? Example,
Pull air from outside, through shade and into a bed room/ roof or back outside. This way their is little heat in grow room. BUT you still would need another exhaust. But that exhaust will have a carbon filter and a fan and if that was on a timer every once and a while you could very well get your PPM up their no problem
Do you kinda get what I mean about pulling air from another place, instead of grow room, that that air will pass into shade and back outside the grow room. The idea is that the fan will pull hot air from the shade. Now for this to work you must have a sealed shade and a cover at the bottom of the shade. Did u buy that type of shade?