The natural byproducts of burning any hydrocarbon and oxygen are CO2 and H2O
Does not matter how the fuel is burned. Although Quartzsite should be fairly dry.
+1 for reviewing the furnace ducting to improve efficiency. The bad sign is when you can hear the burner cycle during the heating process. This indicates the firebox is overheating due to lack of airflow. Need to fix the existing vents or add some additional vents to get more air.
My floor floor vents ducting was installed very poorly. Tried various improvements and finally just added two more ducts. Made a huge improvement and no more cycling against the high limit switch. Tons of heat now and less 12v power required.