Hi, I have an EKO40Supper that has a blower port that is about 1 3/4" x 2" (that is if memory serves me but that is hard to tell as I am often forced to look for it). The air supplied supports a variable primary combustion nozzle with 8 sq in area and two variable secondary combustion tubes that I haven't looked at in a long time. Regardless of the size of the nozzle and the combustion tubes the heat exchanger has 8 tubes with a total area near 25.5 inches and the exhaust (chimney) @ 6" has 28+ inches and an 8" is just over 50" of area. Since there is so much diversity in actual design among models and manufacturers how would one know if the model they are looking at is truly designed in a scientific/mathematical manner that would yield optimum performance? Where does one find the actual equations for mass/energy displacement for comparison? Then in an offhand sense...since water-counterflow is best for water/air handlers why is gasifier exhaust not constructed in a counter-airflow manner to elicit peak performance (that is where water is heated in a manner where the flow directs it to the coolest [exhaust] part of the heat exchanger first and the hottest part last)? With the prices of some of these things (gasifiers that is) is it for the sake of expediency, safety or the dollars and sense (pun intended) side that we are sold a decent product but are not sold the most scientically accurate design for our money?