That marketing doc appears to be skewed. It looks like there is a mix of standard EPA outputs with maximum EPA outputs. Look at the the Jotul F600 v PH for example. The number for the Jotul is not the maximum output. I'm not knocking the PH, but it is not more than 2x as efficient or twice the max output of the Jotul.
Also, most of us don't burn 2x4s. Cord wood is a better measure of max output.
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Cord wood might well be a better indicator of maximum output. Two problems: there isn't an independent lab that is testing all stoves on level ground with same species/same moisture content/same density cord wood; cordwood BTU ratings we are getting from manufacturers are wildly out of line with EPA test results with dimensional doug fir. While some manufactures claim 20 percent increased BTU output, some claim almost 300 percent.
So, for the time being, for comparison, the best we have is EPA test results, which are level ground test results. Doug fir has about 17 -18 million BTU per cord, not much different from many of the lighter hardwoods, Sugar Maple has 23-23 million, and oak and ironwood,locust etc maybe 26-27 million (rough ranges without checking the charts). So one can reasonably extrapolate that sugar maple will give about a third more BTUs than EPA testing, and Ironwood/oak etc about 50 percent more.
If you Bing or Google the following: "List of EPA Ceritfied Wood Stoves - U S Environmental Protection Agency", you will get the complete chart of all stoves tested, EPA emissions results, minimum and maximum BTU output per EPA test, and either default or measured efficiency.
I believe you will find Woodstock used the high end result on those tests for the stoves they have in their chart. I do not believe they skewed the chart.
Furthermore, Woodstock is very conservative in their claimed cordwood BTU heat production for their stoves. While the Fireview tests at about 42,000BTU (all these following numbers are from memory and are substantially accurate), Woodstock gives an EPA of 42,000 and cord of 55,000 - about 30 % higher, pretty much in keeping with what one would expect from the sugar maples, for instance. The Progress Hybrid tested at over 71,000 BTUs, and Woodstock claims 80,000 easily with cordwood - only slightly more than 10 % more than the EPA testing. I suspect with really good, dry dense hardwood you'd really get closer to 33 to 50 % more heat than EPA testing.
I'd like an explanation I can understand of how a stove EPA tested at under 40,000 BTUs can claim a cordwood output of 80,000 BTUs, assuming a normal method of burning at a high output: that is, not continuously loading the stove every hour or two. I'd also like to know how a stove tested at 40-45,000 BTUs can be compared to the PH, tested by the same agency to 71,000, in maximum heat output potential.