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[cando attitude]

Hi Jreimer,

I like your approach to determining efficiency.  I am curious as to the equation you used in determining the O2 and CO2 outputs via molecular weights.  Also, with respect to the amount of water formed as a result of combustion, I am curious as to the mass of water that's simply run through the stove with the forced draft fan (assuming the 250 has one) relative to water vapor produced via combustion.

Cando

[willieG]

efficiency? Whats that, with the ole home built tank in a tank, throw in a wheelbarrow full at 5 pm and go back out at 10 am and take a guess on what you will need for the rest of the day.

I worried about efficiency when I was paying for every btu I burnt. Now, thanks to some sea container that was likely bringing in some fake  garments from some sweat shop from some Asian country that landed somewhere in the good ole USof A, that little emerals ash borer has killed off about my whole bush (except for what the dutch elm disease gets) and has supplied me with so many trees to cut....WHO CARES about efficiency......not ME!

[jreimer]

I like your approach to determining efficiency.  I am curious as to the equation you used in determining the O2 and CO2 outputs via molecular weights.  Also, with respect to the amount of water formed as a result of combustion, I am curious as to the mass of water that's simply run through the stove with the forced draft fan (assuming the 250 has one) relative to water vapor produced via combustion.

I've got the calculations back at the office so I'll get those to you next week.

With the cold, dry air up here in winter, I don't think the mass of water brought in with the incoming air would even register in the equation.  Also, the incoming air moisture is already in gas form, so there is no phase change to suck additional energy, unlike the evaporating water in the wood.  However, I'm thinking that bringing the incoming air (and moisture) up to the exhaust gas temperature is where a good portion of the 30% efficiency loss would be.    If only there was a good way to bring the incoming air up to 250 degrees without cooling the exhaust temp too low... Oh well, it's not illegal to dream... yet.