Originally Posted by pvangel
The heaters have a automatic shutdown when it senses a lack of oxygen, probably would leave in front of a vent or open window. Also will have a CO alarm.
Remember that sufficient 02 does not mean there isn't an excess of CO. You can get CO poisoning with 21% oxygen. Your trusting only the CO alarm.
I'm not saying that using this will kill you in the event your CO monitor fails, but you may wake up with massive headaches and mild retardation.
Edit to add: CO is slightly lighter than air. Keep that in mind.
If you're only using it for a short time and shutting it down while sleeping, go for it. I wouldn't trust an unvented hydrocarbon burning heater in an enclosed box while asleep though. Do they have a vented version of that heater? I'd be interested in that.