Open Flame vs Catalytic Heater

[Loren G. Hedahl]

I have an idea this has been addressed before, but I haven't been able to find a reference that addresses it here --

What is the difference between burning propane via open flame versus catalytic heater in regards to:

1) heat output per quantity of fuel used
2) oxygen depletion per quantity of fuel used
3) water vapor generation per quantity of fuel used

The reason I ask is because we let a very old veteran trailer camper friend stay in our Scamp for several days while visiting us. He is too old to camp on his own anymore, but when he arrived he was as excited about our Scamp in the drive as he was about visiting us, so I asked him if he would rather stay in the guest room, or the Scamp. There was no hesitation and you know the answer.

It turned out that he had built several home-built trailers in his younger days about the same size as our Scamp. When it was over he said it was wonderful to have his own little mansion while here. The only adverse comment was why did we not just put a couple of large clay pots over the stove burners for heat rather than go to the trouble and expense to install a catalytic heater.

After considering it for some time I wonder too. For some reason I would guess that the answer to the three questions above is: the same whether open flame or catalytic.

[Parker Buckley]

What is the difference between burning propane via open flame versus catalytic heater in regards to:

1) heat output per quantity of fuel used
2) oxygen depletion per quantity of fuel used
3) water vapor generation per quantity of fuel used

I'll take a cut at it, and expect others will jump in as well. For complete combustion (100% combustion efficiency) of the propane, the amout of heat generated, oxygen depletion, and water vapor generated (and carbon dioxide production) will be identical. That's a simple chemical formala. However, the big difference is that the catalytic heater will get you much, much closer to 100% combustion efficiency than the stove flame will ever be. And the really serious part of this is that incomplete combustion of hydrocarbon gases like propane generates carbon monoxide, and we all know the result of that. I've heard of the clay pot idea, and I guess you could do that before going to bed, ventilating the trailer the same as you would be while cooking, then shut everything down for the night. I'd never ever go to sleep with the stove running. If you trust the catalytic heater to not generate carbon monoxide, I suppose it's reasonably safe to sleep with it on, provided you have enough ventilation to replace the oxygen it uses. I think some folks do that.

Hope this helps.

Parker

[Doug Mager]

What do you think of using a small Alec Tric micro-furnace instead? Less chance of fire, etc.

[peterh]

Both Doug & Parker make good points. When we have hookups Lynne and I drag out our electric cube heater, which uses no propane, so it makes no water vapor, consumes no O2, and creates no carbon-dioxide or carbon-monoxide and even has a built-in thermostat.

As for open-flame combustion, they create almost exactly the same amount of water vapor and carbon dioxide as catalytic or ceramic heaters do, but open-flame combustion (like on a stove top) burns less efficiently. Whenever you see a flame that has a yellow or orange fringe, that means the combustion process is incomplete,m so you're not getting all the heat you could out of your pound of propane; worse yet, that inefficiency means the flame is creating deadly carbon monoxide. I'm OK with using a ceramic (e.g. Mr Heater Portable Buddy and others) heater, which burns very efficiently and has an entirely blue flame once it warms up, but I'd never use an open flame or stove-top flame, which always have yellow or orange fringing for space heating.

Beyond that one point, catalytic systems offer advantages open flame and ceramic heaters do not. Catalytic heaters put out the same total amount of heat per pound of propane burned, but spread the combustion process out over a larger area so they don't burn as hot. That means you can sit closer to a catalytic heater without getting fried on the side facing the heater and the larger heated area allows more air to warm as it passes by the face of the heater, allowing the heat to circulate around the trailer more evenly.

[Pete Dumbleton]

The difference between the clay pot system and the cat or vent-free systems is that the clay pot has zero safety built in esp in the case of oxygen depletion (cross ventilation to replenish oxygen is a USER responsibility).

Forget the noxious gasses that can be part of all the combustion processes; the clay pot flame will be burning on long after the sleeper has expired from lack of oxygen and I doubt that either a CO or CO2 alarm will have sounded.

All the clay pot does is change the range flame heat to radiated heat.