I can't tell you exactly what the problem was with the generators. They were working correctly, and yes I checked the burning. I believe I was fighting issues caused by the burners for well over a year until I figured it out. I was having weird issues that just didn't make sense. I felt like I was losing my mind. When I started ventilating, along with supplementing c02 I did fine when I would exchange the air every couple hours, but ultimately it just didn't seem worth the effort, and I am getting great yields without dealing with c02 at all. I did a lot of research. There are some forums where others have come to the same conclusion about propane burners. Those people, and I feel like they are generally not ideal for a completely sealed room. Theories are very small amounts ppm of some off gas, or ethylene build up. I know it works for some people, and like everything in this business there are many variables, but for me it makes more sense to ventilate or use c02 tanks. Not to mention the vpd thing doesn't really work if you bump up your temps to take advantage of the c02, and I have been seeing good results focusing on vpd.Sorry to get off topic but what issues are you having with the Co2 generators? Are you implying they are giving off something harmful in your sealed room? How often were you purging the room to fix this and did you inspect the burning to see if it was a mechanical issue?