There are horizontal ducts that carry the exhaust through the bench mass before turning up and out. They can be long and winding.
paul wheaton wrote:... hauling in lots and lots of rocks and stacking them around his wood stove.
And then we all jump out and yell "surprise! we got you this tiny ad!"
September-October Homestead Skills Jamboree 2019https://permies.com/wiki/118704/permaculture-projects/September-October-Homestead-Skills-Jamboree