Thank you for the chime in!

In that post (sorry about the length) I describe a "feed and bleed" system if you will. The burner runs during the light cycle constantly and the atmosphere is exchanged at a rate that maintains proper ppm. Leekage and plant usage doesnt play much into the equation since it is a feed and bleed system once the equilibrium is established (i.e. you find the right fan speed setting to keep atmospere at desired ppm)

These are not blue flame burners, it is a 100% catalitic reaction. Heat is released, but with only 800 BTU to get rid of the fan speed should do the trick.. I have also considered mounting a few feet of 4" drier duckting to the burner so I can put it a few feet from the grow area and have my intake fan sucking on it. The metal ducting should also dissipate a good bit of the heat.

What I have been doing since I imagined this up last night is just setting a burner in the closet that has the grow room in it. My actual grow room is only about 50sq ft in about a 120 sq ft closet and I typically leave the big doors of the closet open with a fan cirulating air in and out of the closet and the A/C vents in the house slightly throttled to give the room a little more A/C .

When I lite the burner I close the closet door and let it run to fill up the closet outside of the growing chamber (and inside as it circulates). Since I am still waiting on my atmospheric analizer to be delivered I only run the burner for a few (~10) minutes at a time as not to overdo the ppm CO2. I am getting about a 1-1.5 degree rise in temp while the unit is on and then I shut it off (stick my arm in the closet, hit the switch, shut the door asap) and let the CO2 circulate while I watch room temps on my $20 wireless indoor/outdoor thermometer in the other room (the "outdoor" sensor is in the grow room). Temps climb another few degrees over the next hour or two due to the lights but stay well within limits. When room temp gets to about 83F I open the closet door and let it circulate out.

Once I have the meter I will be able to set up a feed and bleed ratio where I dont have to do all that. I am also going to go get one of those 800 BTU heaters instead of the 1500 I have now.