Wasting space on here is what I do best
Mind if I ask how you measure "output"
No one is saying that a fire-box full of hedge has way more BTU that a box full of cotton-wood. The hedge has about double the heat content.
What I am saying is....The cottonwood, being so much less dense and faster burning, seems to produce a hotter fire quicker. It just dont last as long. If things were linear, and the hedge was exactally 2x's denser and with 2x's more BTU, one would think that it would burn 2x's as long, or that the cotton wood would burn up 2x's faster.
But what I have found is that the cotton wood burns 3x's faster. And at only 1/2 the BTU's, it seems to heat up the garage quicker. But at the cost of loading the stove 3x's more often.
Like I said, BTU dont factor in time. So what would heat a garage up quicker......
15000 BTU's burnt in 3 hours (1/10th of a cord of cotton wood (12.8cu ft) or...........
30,000 BTU's in 8 hours (1/10th of a cord of hedge)
????
Thats all I am saying. Again, I know hedge is much better firewood and much longer lasting and the ability to get more BTU's in the firebox. But the hard dense woods dont heat my shop up as quick when going out there on a cold morning and its 40 degrees in there.
Kinda like torque vs HP (since you are a car buff). Torque is just a raw number. A measure of how much work CAN be done. HP adds that time factor...how quick that torque can be applied.
When dealing with propane furnaces and such, they are rated in BTU/hr. Wood cannot be rated that way because how fast it burns depends on too many factors.