Originally Posted by Curmudgeon
Well, based on Capt. Sully's response (and others) I'm not going to worry about CO2, but I'll be sure to have a couple of CO detectors with fresh batteries in my new boat, which has a propane stove and cabin heater. I know it already has a couple of propane sniffers.
The reason for my original question was that I've done a fair amount of winter hiking, and one hears the stories of people going to sleep with a Svea running in an improperly vented tent (such as one covered with snow) and not waking up. I had thought it was the CO2 concentration that killed them, but maybe it was CO.
The Svea incidents happen because it does not have a chimney.
Using one of those in the cabin/tent would be akin to lighting
a pile of wood or diesel on your salon
table and hoping you don't die from CO (or in that case, using up oxygen, too).
After years of experience heating my boat with a wood stove, and briefly with a Dickinson
, I can assure you it is the chimney that makes all the difference. Since the Svea has no chimney, it is just like using the galley
stove (which also has no chimney).
stove is a surprisingly large emitter of CO (and some CO2 as well as use of O2, but that's not what kills you first). We find that our CO alarms always go off if we don't open up the boat completely when cooking
in the winter on the galley stove. For this reason, we do most of our winter cooking
on the wood stove.
The galley stove is far more dangerous to life than a natural draft (aka with a chimney) heating device. The Svea is basically the equivalent of a galley stove in a tent.
The key is to picture the air flow... your exhaust
gasses should all be going outside the boat (via chimney in my example). If they are not, you are going to create CO (and also a little CO2 and use up a little O2), but it's the CO that kills you.
Now, having a propane heater makes things just a little more challenging because propane doesn't smell bad when it backs up like a wood smoke or diesel smoke. You won't have that extra warning of smelling a little smoke to remind you that something isn't right with your air flow. Some things to be sure of:
1) CO detectors (two is great) are a must
2) Is there an adequate vertically rising chimney with no more than two 90 degree bends in the pipe?
3) Is the chimney of adequate height?
4) Is there a proper "charlie noble" or "smoke head" attached?
The above will greatly reduce the chances of the propane exhaust
However, you still need to be careful to have enough venting (cracks in companionway
, etc...) to keep up with the draw of the chimney. In most cases boats do, but be sure this is your case. If not, you will have to open up a vent here and there to get air moving.
Also, avoid creating a low-pressure situation in your cabin by opening a port that is downwind on a windy day. This would serve to suck air out of the port, out of the combustion chamber, and *down* the chimney. Exactly what can cause you to get CO in the cabin.
Propane will take more vigilance than wood or diesel since you can't smell it backing up.
Multiple CO detectors would be my choice as well if I were heating with propane.
Either that, or one of the propane heaters that is sealed off from the cabin entirely, drawing its own combustion air in through a dedicated vent, and exhausting its fumes through another dedicated vent.
But, to be completely honest, I would be nervous heating with propane and a natural draft stove because there is no warning that it is backing up aside from your CO detectors. (just a personal feeling... many do heat with propane)