Actual length of wood for an EKO 40?

One of the stoves that I've considered in my research was the EKO 40, but according to their specs it'll only accept a 20" length of wood. I thought I remembered reading on here that measurement is incorrect, and the stove would accept a longer piece. Can someone verify for me? My issue is I want a gassification stove, but I may have to supplement my available firewood supply with firewood that I buy, and 24" is what's normally available. Thanks in advance guys, for this, and all the info I've learned in my short time here. What a great resource this site is becoming.

cut you wood 2" shorter than the length of the firebox, Eko 40=18"