I tried propane for CO2 but my temps got too high, too fast. So I made an alcohol lamp by soldering a couple copper tubes on top of a mason jar and using tiki lamp wicks with 99% methyl hydrate from the hardware store. Expensive. My gas line with a capped "T" is right outside the grow room and I figure I could tap that and run a line for a small burner. Natural gas is so cheap here that I should be able to keep enough CO2 going for pennies a day. Would still rather get a proper controller and run the CO2 off the tank. A lot safer and cooler.