The Toolbox: September 2012

Advertisement Q: We are considering replacing an old deck oven with a new one. Do you recommend thermal ovens? Ken, via email A: In a traditional convection oven, the burner heats air that is circulated throughout the oven decks. The circulated air heats the stone or steel decks. A cyclothermic, or thermal, oven heats oil that circulates throughout the decks. This thermal heating is available in both deck and rack ovens. The heated oil supplies a gentle radiating heat transfer and a fast recovery time between bakes. The benefits include even heat distribution with no hot spots on the decks, and they are highly efficient, usually with a 90 percent or higher rating. The newer ovens are highly insulated and supply a saturating steam that will produce quality products. These ovens are more expensive than convection ovens, due to the lack of an internal burner. Thermal ovens have a separate burner that heats a large amount of oil and circulates it via stainless piping. If you purchase one, you need to ensure you have space for both the oven and the burner, which should be located in a separate room if possible. Good heat retention makes them highly efficient and perfect for baking hearth breads. However, these ovens take a long time to cool down. If your bakery needs an oven that can regulate the temperature up and down in the same day, a thermal oven may not be for you. One burner can supply heated oil to multiple ovens. Q: We use a rack oven in our bakery and have trouble with the longevity of the wheels on the racks. What are the best types of wheels to use? Matt, via email A: You should use thermal high-temperature wheels, rated for use higher than 450°F. They are available with grease fittings to help keep the roller bearing lubricated. High-temp wheels also are on the market that are permanently lubricated. You can purchase them by the wheel and bearing alone, or as a complete set including the caster and hardware for mounting. Q: We have a double rack oven and have been experiencing uneven baking. The product on the top of the rack browns before the product on the bottom. How do we fix this? Paul, via email A: Before calling for a repair, check a few things. If your oven has an air filter, replace it if it's dirty–this should be done periodically regardless. Next, while the oven is off and cool, check the inside of the baking area. Forced air is circulated around the baking chamber via vents, and these vents could be dirty or not adjusted correctly. Your service manual should have the variances for adjusting the airflow. Too much airflow in one area will cause an uneven bake. If you have no service manual, contact the manufacturer for the specs. If you are still experiencing an uneven bake, then the problem may be a circulation one, concerning the motor or the unit that circulates the air. If this is the case, you will need to have the oven serviced. Toolbox tip Many different types of equipment on the market operate using compressed air. Actuators and air have replaced electric motors, resulting in low maintenance machines that run quietly, accurately and efficiently. Air compressors are inexpensive, and the amount of air needed determines the size of the compressor required. This is rated as cubic feet per minute or CFM. The higher the rating, the faster the compressor will replenish the air being used from the tank. As the tank fills with air, it compresses–meaning pressure builds inside the tank–to an average of 125 to 150 PSI (pounds per square inch). As the air compresses, it also condensates, creating water inside the tank and airlines. This allows water to enter the actuators that operate the machine, eventually leading to their failure. This is an even bigger issue during the humid summer months. All air compressors have drain valves on the bottom of the tanks, and once a week, or even daily depending on the weather, open the valve to allow the water to drain to help extend the life of your air compressor, and subsequently, your bakery equipment. This can be done at the end of the day and left open till the next shift arrives. Draining the tank also helps prevent rust from forming inside. To help eliminate water buildup during operation, install an air/water separator or an air filter with a desiccant inside to absorb excess water. Several types are available–some have canisters that allow you to change the desiccant once it becomes saturated and some desiccants are reusable. The separator or filter should be installed inline closest to the end of the line, or nearest the machine to which it is supplying air. These simple steps will help eliminate excess water buildup, increase the life of the machines operating on air, and cut back on downtime and maintenance. Have questions about how to keep your bakery equipment running efficiently or what type of equipment is best for your operation? Ask Keith Grant, Modern Baking's Toolbox editor. Send your bakery equipment-related questions to toolboxgrant@gmail.com. Keith Grant is the production manager for Deising's Bakery, Kingston, N.Y.