After construction of the oven was completed it was allowed to cure for approximately one month. The curing phase allowed the concrete and grout to strengthen while any moisture in the oven slowly evaporated. Once the oven chamber and the surrounding mass was completely dry the first in a series of five test fires were lit to ensure the oven burned fuel efficiently and the mass was able to absorb and maintain heat effectively.
To prime or break-in the oven for heavy use in a commercial kitchen a small fire was built in the oven chamber each day and allowed to burn itself out. This process was repeated for five days in an effort to slowly heat up the oven mass. In our case the oven mass consisted of 22,000+ pounds of white clay and sand cocooned inside the cement block and brick column.
When constructing our oven four thermometers were inserted into the brick exterior of the oven chamber. The thermometer probes allowed us to then monitor how the mass absorbed and maintained the heat from the fire. We were very impressed to see how the mass of our oven slowly absorbed and maintained the heat from each of the test fires. Over the course of the break-in period the oven mass gradually warmed to a consistent 600°F (315.56°C)
And although the internal mass of the oven was very hot, the brick exterior remained cool to the touch. The fire-resistant insulation added to the inside of the cement block chamber helped to keep the cooking heat inside while shielding the kitchen staff from having to work in an uncomfortably hot kitchen.
The manufacturers of the Panyol ovens have an excellent collection of informative videos on their website including this short clip about how to build the fire in an oven. Under normal working conditions ovens like Le Panyol Pro 120L are heated to optimum cooking temperature by burning a fairly small amount of wood/fuel. Once the oven mass is to temperature the spent wood, ash, and coals are then swept out of the oven chamber and the heat retained in the oven mass is actually used to cook the food.