Originally Posted by JVallely
Scottyt's right. Though John R Pollard makes some interesting observations, the total amount of heat that comes out of the stove has to equal the heat generated by the burning fuel--no more, no less, counting that which goes up the flue or is otherwise lost to outside.
What heat is radiated after the flame is out is only that which was absorbed by the stove and surrounding objects while the flame was burning. When the stove was first lit, the metal and the boat had to absorb heat before it was hot enough to radiate heat. You might say that's the heat it gives off after the flame goes out.
Baffles, materials etc. make a stove more efficient by controling the air flow to the flame, limiting the flamable gasses that escape without being burned, and limiting the heat that's lost up the flue. They make the stove heat the boat more efficiently, but by themselves don't make it any hotter.
So Medsailor's calculations stand on their own, and don't need to take stove design into account.
You know, I've been meaning to get back to this one. Intuitively, I'm inclined to agree that you (and Scotty) are correct on this.
Yet I do continue to wonder what the advantage to having the appliance is then (other than containing and venting the exhaust). Why not just run the open flame from a burner?
I guess what I mean in part by this is, that when "rating" the output of a heater, does the rating standard or formula only track btu content of the fuel source?
Or, in other words, are we talking about apples and oranges? There is a btu content of the fuel source, and a btu rating of the appliance. But are they necessarily one and the same?
This would seem like a crude way to calculate btu output of an appliance -- seems like any two appliance that consumed the same amount of fuel would always have the same btu rating (the fuel's btu rating). And yet some appliances (heaters for example) are rated more/less efficient than others with identical output.
I still would be interested to hear how the numbers crunch on the diesel version of the Dickinson heaters. This might give us some indication if we're comparing apples to oranges. But I'll let someone else do that.