Propane - rise or sink?

[SkunkedAgain]

I know that propane is more dense than air, and will sink to the ground. However I haven't been able to determine if that's true for the exhaust. The portable ice houses have ventilation flaps higher up. Does unburned propane sink and the exhaust rises?

[Heft]

Raw fuel and carbon monoxide drops when temps are below 32 degrees. I belive the vent flaps on the top would be to vent out some of the combustion air from your heater. Your heaters produce carbon dioxide while there burning (and hopefully if its running right no carbon monixide), and if there was no venting pulling it out the top then it would fill up the air space inside the house and start using up the fresh oxygen and make you feel alittle sleepy. Even though there is air leaks around the bottom of most portables, having the vents open on top is the safest way. Carbon monixide is deadly, but carbon dioxide can be just as deadly in some situations. Be careful.

[81Saluki]

Propane combustion yields 3 by-products: carbon monoxide (CO), oxides of nitrogen, and hydrocarbons. CO is the most dangerous. Since the exhaust is hot, it will rise to the top of the house thus the location of the ventilation flaps. Maintain good ventilation and you should be fine. If worried, buy a CO detector.

[UMDSportsman]

My guess is that it will raise. Logic behind it: The unburned propane will be coming off with the exhaust, therefore it will be at a higher temperature than the ambient air. Since colder air is more dense, the hot exhaust and unburned propane will raise to the top of the ice house.

[Eric Wettschreck]

If you have raw/unburned propane vapor in your fish house, you have a very explosive problem and need to take a look at your heater before you use it again. I'm serious.

The vents higher up in the air create draft. This draft, for lack of a better word, sucks the CO and CO2 vapors out of the shanty. If they were low to the floor the vapors would collect in the house. Similar, in a way, to how a properly operating smokestack works.

[UMDSportsman]

81Saluki- you beat me too it, but as long as you are listing the byproducts of the combustion of a hydrocarbon, you forgot water and carbon dioxide. In a complete combustion reaction you will have the products of carbon dioxide and water. since a complete combustion reaction is not always the case, you will end up with more, some water, some carbon dioxide(CO2), some carbon monoxide(CO), some unburned hydrocarbons (because of incomplete combustion), and some oxides of nitrogen (this is because air is ~80% nitrogen (N2), because of the high temperatures of a combustion reaction, nitrogen can combine in different amounts with oxygen to form NOx).

sorry for the long rambling, just an extra little tid bit

[SkunkedAgain]

Okay, so for the simpletons like me the answer is:

Raw/unburned propane sinks

Burned/combusted propane exhaust rises

Thanks all.