Like the Propex (and others) both the air used for combustion and the
combustion exhaust are from/to the outside of the vehicle.  Consequently no
interior air is used in the heating.  Interior air is pulled in and heated
and blown back into the interior with no mixing with the cumbustion
process.  Consequently no danger of CO or low oxygen conditions.  BUT the
exterior exhaust must be properly located so as not to feed into the
interior.

On 9/25/07, Geza Polony <gezapolony@sbcglobal.net> wrote:
>
> Troy,
>
> Do these heaters have some kind of a low-oxygen shutoff, as the Mr. Heater
> units and others do? If not, how do you use them while sleeping?
>
>
> Geza
>
>