Direct gas-fired (DGF) ovens remain popular, but tend to require higher maintenance costs due to the higher number of burners. That’s why many oven experts, and even the maker of his DGF oven, suggest turning to air impingement ovens or convection heat to stay cool and save a dime.
Babbco Vice President Jerry Barnes said: “Air impingement ovens use focused convection heating with powerful high turndown burners, so temperatures can change very quickly. They don’t rely on hotboxes.”
Additionally, these older radiant heat systems require a very long time to heat up and cool down. Specifically, he pointed out that the DGF oven takes 1-2 hours to preheat, while the air impingement oven heats up in just 30 minutes.
“When you change the product and change the bake profile in your oven, convection heating reduces the wait time because you can change the air temperature more quickly,” Barnes said. “If there is a production gap, the normal oven will overheat, causing the edges to burn in one part of the production process and the product to be thin in another part. It is not affected by heat.”
Ken Johnson, President of Gemini Bakery Equipment/KB Systems, also recommended considering an indirect gas-fired oven, as it uses approximately 30% less energy than a DGF oven. Convection transfers energy to the product more efficiently than radiant heat alone.
“This more efficient heat transfer results in lower firing temperatures in the convection zone,” he added. “Gemini/W&P’s turbulent air zone results in lower baking temperatures, less energy use and even baking.”
He said the zone features equally spaced carbon steel tubes that form upper and lower oven-heated plenums. A mesh belt support grid sits above the lower pipe plenum. Heated gas then flows through the tube plenum, radiating energy into the baking chamber. Recirculated bake chamber air passes between these plenum pipes. In addition, its variable speed airflow is reversible and can be top-to-bottom or bottom-to-top for different products.
Since introducing convection ovens over a decade ago, Auto-Bake has replaced many of its older hot oil ovens with convection ovens, says Scott McCally, president of Auto-Bake Serpentine and Hinds-Bock. .
“Generally speaking, cake producers are reluctant to use convection heating because it cracks the product and creates problems with the crust,” McCally said. “The way we can control top and bottom convection allows us to virtually eliminate all airflow on top of the product that causes these problems, producing a much better product than radiant type ovens. They could bake the product faster and instead of raising the temperature to drive heat into the product, they could lower the temperature and increase the speed of the fan, using the fan as a mechanical force to drive heat into the pan. I can.”
Mecatherm’s product marketing manager Marie Laisne said the company’s M-TA can offer multiple heat transfer modes, such as convection, radiant heat, or a combination of both, in each independent heating zone.
“By providing just the right amount of energy with minimal baking time to reach the required product quality standards, this oven offers an optimal energy consumption solution,” she said.
Johnson said Gemini/W&P offers radiant-only ovens, some zones with combined radiant/turbulent/convective heating, or all zones with combined radiant/turbulent/convective heating. I pointed out that The turbulence zone comes with he two or four blowers for enhancing convection.
Burns said hybrid ovens have been around for decades and likened their versatility to Swiss army knives.
“Hybrid ovens put in your pocket multiple tools that you deploy based on your product and help future-proof your oven,” he observed. You have to adapt quickly to your tastes.”
Joe Zaleski, president of Reading Bakery Systems, says the DGF oven bakes primarily with low levels of radiation and convective airflow. Products are developed and fired in a still air and humid environment. Mixing and matching technology allows bakers to tailor baking profiles to enhance the characteristics of specific products.
“Many hybrid ovens use this very mild heat to develop the texture and flavor profile of the product in the front oven zone, followed by a more aggressive, higher airflow environment in the last zone of the oven. We change and dry the product to its final moisture content,” explained Zaleski. “In this drying area, the heated air hits the product directly, making convective energy more efficient and reducing both heat and air moisture.”
New technologies are also emerging. A few years ago, AMF Den Boer unveiled the world’s first zero-emission hydrogen-fueled tunnel his oven. The Multibake VITA Tunnel Oven provides industrial bakeries with an effective solution that reduces the carbon footprint of the baking process by 99.9%.
Modular ovens use green hydrogen, a carbon-neutral fuel, also known as clean hydrogen. Commercial ovens typically use natural gas as a source of heating, but this new patent-pending technology virtually eliminates carbon dioxide emissions from ovens while reducing utility costs.
For specialty bakeries who prefer rack ovens, Koenig Bakery Systems offers the Roto Passat SE with 20% energy saving potential.
Christian Benedikt, oven design group leader at Koenig, says the oven features flow-optimized heating coils, high-quality sandwich insulation with aluminum interlayers, continuously adjustable steam and control systems. It says to use and minimize energy usage. Additionally, the oven has a double-walled baking door and is made of double steel with rear ventilation to keep surface temperatures down.
He added that the energy efficiency gains could pay off over a year or more. For example, a bakery that is open six days a week saves about 4,000 liters of kerosene, equivalent to about 12 tons of carbon dioxide per year.
With energy prices showing no signs of coming down, bakeries should focus on oven maintenance and explore new technologies.
This article is an excerpt from the July 2022 issue of Baking & Snack. Click here to read all oven features.
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