Ventilation systems located over commercial foodservice operations’ cooklines and in dishwashing areas remove both cooking heat and effluent from the back of house.
The main components of commercial kitchen ventilation equipment can vary but typically include hoods, fire systems, pollution control units, grease extraction devices and controls, as well as exhaust and makeup air systems.
Professionally sized and installed, ventilation hoods are custom-designed for specific applications and equipment lineups. Adjacent equipment will impact hood size and shape. For example, hoods that sit lower and closer to appliances are often used in quick-service eateries with fryer banks or kitchens with low ceilings, while island-style hoods are situated in the middle of a room.
Ventilation equipment is categorized by where it will be used. While type 1 ventilation systems are grease-rated for use over grease-producing appliances like griddles, Type 2 units perform as vapor hoods and are rated for controlling heat and steam produced over dishwashers and certain cooking equipment like steamers.
Type 1 systems’ grease filtration capabilities extract particles from the airstream. The filtering options or grease removal apparatuses the system uses, which range from low-tech baffle systems to high-efficiency extractors, depend on the ventilation process, system design and level of grease extraction necessary.
Hoods also effectively clear the air by discharging cooking odors outside of the building using various processes. A filter-style unit uses carbon to clean the air. An electrostatic reciprocator, or ESP, charges particles as they move through the unit and collects them while using carbon for odor removal. Hoods with pollution control systems remove smoke, grease and odors before they reach the airstream and cause odors.
Ventilation system exhaust fans are most often mounted on the facility’s roof but can also be placed on an outside side wall. Belt- or direct-drive fans are available.
Another part of ventilation systems, makeup air units provide replacement air so that the kitchen’s negative pressure does not compromise cooking equipment operation. Makeup air units compensate for exhaust systems that allow heat and smoke to spill into unbalanced or poorly designed kitchens. The load cooking equipment determines how much makeup or replacement air is needed to balance the environment. The presence of the excess smoke will not only negatively impact air quality but will also raise back-of-house temperatures — and utility bills.
Operators can choose from four different systems designed to minimize air velocity around the hood. One type brings untempered air from outside into the kitchen, while another brings in outside air and heats it. A system is also available that brings in outside air and cools it, and another both heats and cools outside air, depending on what the environment requires. DOAS, or dedicated outside air systems, control both the temperature and humidity of makeup air.
It’s important to note that larger hoods with more overhang and end panels more effectively contain fires. Another ventilation system component, fire suppression equipment and controls, contains or extinguishes fires using mechanically activated chemical agent tanks when a sensor at the duct connection reaches a specific temperature. Systems are available that provide unlimited water supplies for this purpose.
Exterior hood surfaces have become more unique and aesthetically pleasing for front-of-house use. Whether used in the back or front of house, for sanitation requirements, ventilation hoods must be constructed of 100% stainless steel or have stainless steel in exposed areas, such as food zones.
Ventilation system innovation has centered around energy and usage. DCKV, or demand control kitchen ventilation, provides added energy efficiency as these systems automatically vary operation based on peak and slow periods. These units come equipped with sensors or optics that measure heat differences between the hood and the room. DCKV systems can also react to both heat and exhaust. Although these systems can initially be more costly, the return on investment with energy savings is generally less than two years.
Also, energy-saving, electrically commutated motors, called ECMs, easily adjust fan speeds. Systems are available that can control makeup air by zone. Operators can add sensors on some ventilation units to detect CO2, fire and odors.
Operators can include automated cleaning systems or an ultraviolet light option inside hoods to help break down grease in high-volume applications.
