The Basics / How It Works The Exeter processes feedstocks up to 6″ in diameter and a bit over 6′ in length. It is not intended for chipped or shredded feedstock. After loading feedstock and closing the doors, a fire is set in the firebox. Additional fuelwood is added through the firebox doors. After venting away moisture in the feedstock, the flues are capped, directing combustible gases into the firebox for carrying on the process. Combustible gases are conveyed through an internal gas delivery system into the firebox. No additional fuel is need to provide process heat. Charcoal made in the Exeter resembles the wood used as feedstock. Each batch can produce a cubic yard of end product.