Question: I've given the concept of vent-free gas-log combustion some thought (logical analysis, being one of my hangups,) recently, and have concluded that, except for an oxygen depletion sensor and a host of government regulations, the technology is not all that different from the time honored, but frowned upon, practice of operating your gas fired oven as a supplemental heat source.....I mean, the input is the same...natural gas or liquefied propane gas and household air, and the output is the same...heat, carbon dioxide and water vapor. I'm interested in your thoughts on this subject. Answer: It is pretty much the same, except for the amount of hours that they are used. We get warnings in the radio around here saying not to use your range and oven in this fashion. The vent-free logs that are 39,000 BTU are also much larger than most range burners. In addition, they are tuned a bit cleaner since they don't have to fake a yellow flickering flame. So, you are correct...a lot of CO2, Water Vapor and heat..if everything is working good.