conditions dont need to be optimal to benefit from co2

i made my boilerroom into a grow room, it was hot but the co2 the boiler gave off made my plants veg insane

i read somewhere that a house of 4 has twice th co2 in the air as outside and you can add to that if you have old appliances with pilot lights and shit

youd probly be surprised if u test the air but its like 15$ a test if you dont have a meter yet and to go around testing different rooms is fun but expensive

i been thinking of sealing a room to run co2 (have tanks from paintball alrready) but it would be indoors right now and with tanks there is less worries co -co2 as long as you dont burn off that extra oxygen molecule