Not Swedish; French Canadian!
Another Q: did you use the same "flux block"?
One reason I ask, is because sometimes, a testing method has to go to "extremes", to prove or disprove a point. Not saying that your figures are wrong, and I recognize that gathering 500 data points involves a tremendous amount of work, but I'd like to see it done over a few more "flux blocks".
I also have to analyze the method here, a little bit: one possible source of error, may come from miniature temp probe movements, no? Would you be able to find any trend (up or down) in the sequence of data? (assuming that that would be relevant/applicable)
Just trying to tighten up the results...
edit: here's another one: How about calibrating the flux block, by setting each end at different temps, on purpose?