from the sound of it it seems like you have an ac setup of which i described, it wont affect your co2 to much to fret about.
also co2 escapes at varying rates dependant upon how your room is setup and wether or not you have leaks and such, to conserve and still have effective use of your co2 would be to run it only in the day (some people run at night which is pointless as your plants dont respirate at night), and using it after the stretchkng period (week 1/2 depending on strain) around week 2-finish.
co2 in the bottles using injection will help control heat as it produces non and comes out cool but requires alot more bottle refills and co2 by a generator/burning of propane is alot more efficient but produces alot of heat but will last way longer than a bottle, theyre also more costly to setup than injection.