A kitchen hood, exhaust hood, or range hood is a device containing a mechanical fan that hangs above the stove or cooktop in the kitchen. It removes airborne grease, combustion products, fumes, smoke, heat, and steam from the air by evacuation of the air and filtration. In commercial kitchens exhaust hoods are often used in combination with fire suppression devices so that fumes from a grease fire are properly vented and the fire is put out quickly. Commercial vent hoods may also be combined with a fresh air fan that draws in exterior air, circulating it with the cooking fumes, which is then drawn out by the hood.
In most exhaust hoods, a filtration system removes grease (the grease trap) and other particles. Although many vent hoods exhaust air to the outside, some recirculate the air to the kitchen. In a recirculating system, filters may be used to remove odors in addition to the grease.
There are two major configurations of extractor hoods: ducted (or vented) application, and ductless (or recirculating) application. In a ducted application, the output collar of the extractor hood's blower motor is attached to a duct system, which terminates outside the building. In a ductless application, a filter, often containing activated charcoal, removes odor and smoke particles from the air before releasing the cleaned air back into the kitchen.
A ducted system allows for removal of all forms of airborne contamination, while a ductless one recirculates heat and moisture into the kitchen. In addition, a ducted application eliminates the need for regular replacement of the filters, and avoids the airflow restriction (and resultant loss of power) caused by them. However, ducted application can be impractical, due to lack of space or ability to install a duct system, make-up air requirements, or the additional cost of heating/cooling the make-up air. Some range hood designs allow for both types of applications.
Exhaust hoods almost always include built-in lighting to illuminate the cooking surface. In addition, some manufacturers offer matching accessories, such as backsplash panels, pot racks, shelf units, or dish racks. The main advantage of an extractor hood is that it can easily filter the airflow, without harming the edible materials and can be easily installed if it is semi-automatic. Extractor hoods controls are typically electronic, though some low-end models use electromechanical controls. Extractor hoods with electronic controls can offer remote control, motorized height adjustment, thermal sensor, overheat protection, boost mode, delayed shut-off, filter cleaning reminder, active noise cancellation, temperature display, user presets (memory), and so on.
Also known as cassette filters, mesh filters are made from aluminium mesh strips placed one over the other in succession. They are highly effective in the capture and removal of oil and grease from smoke of both ducted and ductless chimneys. With the volume of filtration being high, these types of filters need to be cleaned once every week.
These type of filters are made out of steel/aluminium frames with curved panels. The curves in these panels are capable of catching up on grease, oil and other such particulates. Highly durable and easy to clean, they need to be cleaned once every month and are used in both ducted and ductless chimneys.
Charcoal filters are made out of fine powdered activated carbon charcoal that is in a honeycomb structure. Used primarily in a ductless chimney for the filtration of odors, a charcoal filter has no cleaning method and is usually replaced once every 6 months or so.
In order to clean a kitchen hood filter, the simplest method is to use baking powder. For this, the hood filter is placed in a large pot of water, drop in half a spoon of baking powder. This pot with the filter and the baking powder is now heated to boil on a stove. As the water boils, the grease and the dirt can be seen being removed slowly and steadily.