HOODS Hood Components
Grease Filter: Devices required in Type I hoods that prevent flames from penetrating into the ducting above the hood Fire Suppression System: Designed to detect and extinguish flames with a suppressing agent. These are required for equipment that produces grease- laden vapors and must be tested and comply with UL Standard 300 Pollution Control Unit (PCU): A device located in the duct run between the hood and exhaust fan to reduce smoke, odors and other emissions. They are typically installed when mandated by local building codes Exhaust Fan: The driving force of the ventilation system, located on a rooftop or a sidewall and are designed to keep air circulating properly in order to minimize excess smoke accumulation Electrical Control Panel (ECP): A high-voltage panel that controls the exhaust and makeup air fans as well as any other optional components such as self- cleaning systems, remote monitoring and diagnostics Makeup Air Unit (MUA): Keeps the building’s airflow properly balanced by replacing the exhausted air expelled from the hood and exhaust fan, known as “makeup air.” For maximum efficiency, heating and cooling of dedicated makeup air is delivered at or near the exhaust hood, with the unit typically activating between 55°F and 85°F. Makeup Air units are also typically offered in several different designs:
• Front Face Discharge units move makeup air outward through louvers or perforations in the front face sheet metal, sometimes at a downward angle • Air Curtain designs typically introduce makeup air in a downward direction at the front edge of the hood, inward from the louvers or both • Back Wall Supply units convey a portion of the makeup air downward through a plenum located in the back of the hood, then discharged downward behind appliances or forward toward appliances. This design is a popular choice when space is limited • Perforated Supply Plenum (PSP) units are located on the perimeters of the hood on the upper outside front of a wall canopy hood. They direct makeup air downward through two layers of perforated metal to promote downward laminar air flow Exhaust Ducting: Round, square or rectangular metal conduits designed to channel cooking effluents from exhaust hoods to exhaust fans. These must be cleaned periodically, typically every six months. They are available in two options: • Factory-built sections couple together with strong, leak-tight joints • Fabricated in-place ducting sections are welded together at the jobsite
Best Practices
• Use dedicated makeup air supply units with partially tempered air discharged close to the hood face • Direct-fired gas heating for dedicated makeup air is recommended when local codes allow • Use a Direct Outside Air System (DOAS) in high- humidity areas • Install only listed hoods, ducting and fans as well as an electronic detection fire suppression system when using solid fuel sources
• Hoods should be properly sized in order to reduce exhaust flows at maximum cooking rates • Group appliances by duty, use direct-drive, variable-speed fans with demand control and install end panels to maximize exhaust flow • Increase overhang for heavy duty appliances and single-island hoods • Use the best available grease filters for maximum grease removal • Install pollution control units to reduce smoke and odors
EQUIPMENT GUIDE
38
Made with FlippingBook Learn more on our blog