If it burns cleanly/completely then it will only produce carbon dioxide.
However, as a safety measure, you'd better have carbon monoxide detector
in/around your house (or bed room.) In fact anything emitting flames
inside your house has the "potential" to produce carbon monoxide that
kills. Least to say it also has the potential to cause fire that kills.

FC

eric wrote:
I just bought a 23000 BTU spaceheater at Walmart and on the outside of the
box it says that it does not require a vent to take any exterior vent.
How is this possible?
I would like to use it this winter but i would rather not kill me and my
family.