We don’t recommend using charcoal as a heat source in our ovens. Charcoal contains accelerants and chemicals that can be detrimental to the oven, as well as they aren’t safe for consumption.
We suggest that you use a hardwood like a mesquite, apple, hickory, maple, etc, and ensure that it doesn’t contain accelerants or harsh chemicals of any kind. Accelerants and chemicals can also be difficult to manage when heating the oven, and could potentially cause damage to the oven itself. You should stack the wood in a tic-tac-toe fashion, at least 12-14” apart for optimum results. Remember, the fire heats the tiles and the tiles are what cooks the pizza through.
