Nope!

YEP! Do your research -- the gas piped into your home is not pure methane.
It is typically around 92% methane with the remaining 8% consisting of a
variety of other substances, including some contaminants depending on the
source, processing, and transport. This is a well known and documented
fact -- documented even by some utility companies right smack dab on their
web site.

The point is that the burning of gas within a closed space affects air
quality. How badly depends on a variety of factors such as placement, gas,
efficiency of the burning mechanism, and so forth. Whether the affectation
is minimal or significant enough for concern is open to debate.

Since providing "excess" air to a ventless fireplace doesn't reduce the
efficiency, that's how they burn gas. The result is that the health
hazzard isn't CO but oxygen depletion. The units all have the pilot light
positioned so that if the O2 levels go doen, the thermpile gets cold and
the
unit shuts down.

It would have to be a fairly well closed up room for the oxygen levels to
deplete. As we discussed elsewhere in this thread, these detectors have a
threshold that is awfully close to the minimum levels we require to survive.
Not 'xactly what *I* like to hear, but if it works for others....

I have a digital CO detector very close to my ventless unit. It has
never
gotten off ZERO because of the ventless burner. (It has responded to
cooking on my ELECTRIC stove.)

Hmmmmm....

James