I'm planning on replacing my old 1979 VC Defiant with a Jotul Oslo. Yes, after all of the posts about how much wood they burn and how little heat they produce, I'm still on it. I might be one of the slower members of the forum! Here's the setup and then my question: I see numerous posts about how a BK will use 1/3 less wood than many stoves - including the Oslo. There are also many posts about how the Oslo, "eats a lot of wood". There have even been posts that say that the Oslo really produces very little heat! As you can imagine, I'd be pretty unhappy with a stove that burns a lot of wood and produces very little heat! The Oslo has an HHV of 74% - a BK Princess has an HHV of 81%. That's a difference of 7%. That BK is doing some good stuff there, but it's only a 7% difference. How can that translate to using 1/3 less wood? Trying to understand why I can't use the HHV ratings to get an idea of how efficient the stove is in terms of wood usage and how much heat it will put out from a given load of wood.