First of all I assume OAK stands for outside air supply? Not sure where the K comes from but anyway.. I have a Drolet Eco-65 and after inspecting the fresh air supply on the stove with the side doors off. It appears there is a big space between where you attach the air supply duct to the stove and the actual internal duct to the combustion part of the stove. I assume the outside air supply is not intended to be 100% outside air but only a portion? Just wondering?