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What are the differences between hood manufacturers?
There are differences in construction materials, construction quality, air capture enhancements, whether or not the hoods are registered with a listing agency and most importantly, CFM ratings for particular equipment types. Hood surfaces may manufactured with of stainless steel, aluminized steel or galvanized, depending on where the surface is located. Stainless steel hoods are most durable and attractive, though only the exposed surfaces inside of hood and the outside visible surfaces need it. Complete stainless steel construction is available for additional cost. Stainless steel comes in different grades and some manufacturers cut costs by using a lower grade such as 420. We only recommend 304 SS for it appearance and pitting resistance; the few dollars saved are not warranted. Some manufacturers have devised clever modifications to enhance containing the effluent at the edge of the hood; these include a performance enhancing lip and small jets of air around the perimeter of the hood opening with a separate fan. These are reasonable concepts. As mentioned, hoods may either be listed or non-listed, the latter having to meet the requirements of ASHRAE and NFPA 96. Listed hoods are rated by their successful testing at UL or other testing agencies. Exhausted air volumes may never be less than the listed amount, but may exceed them.
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