There is some kind of insurmountable wall blocking communication between us in this thread, I can't figure out how to climb over it. Lol. I wasn't saying there is no such thing as a sealed room, just that yours isn't, based on my best interpretation of what you've written so far.

I think you are exactly right Harv. It feels kinda like this when I'm trying to communicate sometimes. And the sad thing is. I don't know what to do about it. Maybe I will snap some pics.

Yeah, I'm curious to see what you were describing with the water heater.

Now that I'm thinking about it again, I'm just sitting here on my computer all stoned, haha, I think I was a little off track with a couple ways I was thinking about your setup earlier.

I still don't know if you have an exhaust fan, but the best I can tell so far, when your ac is on, you're diluting your co2 with fresh air.

I got stuck on thinking that your setup was like mine, and it isn't, you said you have the exhaust from a gas water heater going into your room, plus co2 coming from a tank controlled by a co2 controller? So whenever your ac comes on, you don't have a burner coming on and fighting the ac with heat like I would. I wrote that before because I was just being dumb and thinking that's what my setup would do if I had my central ac plumbed into my room. Lol. But it's still not good, even if you're not adding heat, if you're wasting co2. I get what you're trying to do though, you're basically trying to tie your existing systems into your room, to maybe save a little money if you can, right?

When I had my aero system going, I had my central ac plumbed into my room, with my exhaust fan pulling it out. (The exhaust fan would pull air in through the vent whether the ac was on or not.) I also had a window ac in the wall between the room and the rest of the basement, which came on if it got too hot. As you can imagine, this system was't ideal. I found myself having to run my house ac more, just to keep the room temp down. If I didn't turn the house ac down, the window ac would come on, add heat into the basement, and then trigger the house ac, which would then have to take that back out. Running 2 ACs instead of one really killed my overall efficiency, resulting in a power bill nearly 42% higher! Needless to say, once I got that bill, I never ran it that way again.

I've rebuilt my whole setup so many times I've kind of lost track, but at some point I ended up with my current most efficient setup, my co2 burner and dual hose portable ac, combined with sealing all the cracks, gaps, etc in the room with expanding foam, adding weatherstripping to the door, completely removing the previous central ac duct, etc.

But yeah, I take back what I was saying earlier about your co2 adding heat, if you have a tank, definitely no added heat there. Stupid me. Lol. But you'd still be able to save power I think by using a dedicated ac system, and truely sealing the room, and you'll definitely save co2 doing that also.

Here's something just for the sake of comparison. If I'm in my room, my co2 burner won't come on, or if it does, it won't come on much. Target 800ppm. So my base metabolism is almost enough to maintain that target co2 level against the plants taking it out. (When I was building the room, it hit almost 2000ppm just from me working in there, before the plants were there.)

One more thing, that window ac I had between the room and the basement, that thing is awesome for the winter. The window ac moves all of the waste electrical heat, and heat from the co2 burner out of the room into the rest of the building, tremendously cutting the gas bill. I don't remember the figures, but when I calculated it before, I remember thinking, damn, the increased electrical cost of the grow room is almost balanced out by the reduction in the gas heating bill! I sure wish I could figure out a way to get it that efficient in the summer..