New Restaurant Guide

Combi Oven Playbook

Can I omit the ventless hood and still comply with the International Mechanical Code? While ASHRAE Standard 154 lists Combination Ovens as hooded appliances without an exception for removal of the hood, the  current version of the International Mechanical Code allows for some grease and smoke producing appliances to be installed  without a hood, where the measured grease emissions from the product do not exceed a certain level. This exception is granted  where the design of the space includes the heat and moisture loads that are produced by the appliance, and the space is well  ventilated and properly air balanced. In most of our existing restaurants we will not be able to meet the intent of this code, even if  the Combi Oven testing indicates we are below the limit for grease emissions.  Why aren’t we requiring a fully vented hood as a standard? While there are significant benefits to a fully vented solution and many jurisdictions will require them in lieu of a ventless hood,  there is an added cost and complexity that may be a challenge for many of our existing buildings. The addition of a vented exhaust  hood requires at least that same amount of makeup/transfer air to be introduced into the kitchen. This could be a challenge for  some operators with aged or inadequately sized rooftop units serving the building and may require an additional/replaced RTU to  meet the needs.  How do I know if my site’s local jurisdiction requires me to install a fully vented exhaust hood? The installation of a Combi Oven extends beyond the scope of just the Oven itself and will require coordination with the local building  and/or health departments to verify any permitting requirements for the electrical, plumbing or relocation of kitchen           equipment, along with any requirements for a fully vented exhaust hood. Some areas of the US also limit the number of ventless  hoods than can be installed in a kitchen to a single unit, and may require vented hoods where more than one Combi Oven is present.  What happens to the grease that is released from the Oven during and after the cooking process? A fully vented hood provides the best grease and smoke removal solution, but a ventless hood can be an acceptable and potentially  less costly alternative for many existing restaurants. The introduction of grease into the space without a hood would likely contribute  to noticeable grease build up over the first couple years of operation, maintenance costs would not only include the unit’s      filtration needs, but also replacement of grease stained ceiling tiles and FRP within the space. There is also potential for safety and  slip hazards with grease build up on the floor.  Why are odors a concern? Don’t we all like the smell of cooking bacon? While a vented solution will remove most of the odors from the cooking process, the ventless solution will do more for grease and  odor removal than an unhooded Combi Oven. Previous Combi Oven baked goods testing (no proteins) with apple pies fared well, as  customers liked the smell of the fresh baked pie. Steam cycle cooking for proteins, which can include items such as bacon, eggs and  chicken, will release very different odors into the space. Poorly ventilated and negatively pressurized restaurants will have challenges  in controlling the spread of the cooking odors and the grease‐laden air. As the smells settle into materials throughout the building  over time, it is not likely the stale odors will be deemed favorable by customers and crew. (Think of what 2 year old bacon grease  might smell like!)  Does the ventless hood remove heat from the cooking cycle? No, the ventless hood can actually produce additional heat on its own, in addition to that of the Combi Oven. The ventless hood  removes significant amounts of grease from the cooking cycle and a minimal amount of moisture, but the heat and some of the  moisture from the cooking process is ejected back into the space by the ventless hood. Restaurants that are currently experiencing  comfort issues in the kitchen may be worsened with the added heat and moisture loads from installing the Combi Oven, even with a  ventless hood.  How can I prepare/maintain my HVAC system, to handle to loads from the Combi Oven? Proper HVAC maintenance and routine air balancing (every 3‐5 years) to ensure a well ventilated space will support the HVAC  system’s ability to handle the added grease emissions (along with the added heat and humidity) within the space. If after an air  balance your kitchen is still experiencing high temperatures and/or humidity levels, an Engineer should be retained to evaluate the  unit sizes and kitchen loads to determine if additional cooling is needed for the space.

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