One of the first criteria to consider when you select a range hood is the ventilation system. There are two main types of hoods: ducted and ductless. If it’s not possible to install ductwork to draw foul air outside, you need to turn to a recirculating hood. On the other hand, if it is possible to install a duct, or if there is pre-existing ductwork, you should install a ducted hood.

Ductless hoods - recirculating
This type of hood operates as follows: a charcoal filter cleans foul air, removes most grease particles and odours and returns the air to the kitchen. These hoods are considered less effective than ducted hoods, since they return air back into the kitchen without extracting smoke, heat or moisture. Ductless hoods are simpler to install.

Most recirculating ductless hoods are installed under wall cabinets, including microwave integrated fans. Some manufacturers offer convertible hoods: recirculation modules installed on ducted hoods. This is an option that is available for nearly all hood models, including chimney-style and island-mount hoods.

Ducted hoods - extraction
This type of hood completely eliminates foul air, venting it outside the house through ductwork. These hoods are very popular and constitute the most effective way of meeting ventilation standards as set out in the National Building Code of Canada. Installing a ducted range hood is more complicated because of the ductwork involved; once that is in place, installation of the hood is quickly completed.

To be effective, the hood should be positioned above or very close to the cooktop. It is therefore the location of your cooktop that will determine the hood model you should install.

Standard hood
These under-cabinet range hoods are by far the most popular. They can be vented outside through ductwork or ductless, whereby air is captured, filtered and returned to the room. Ductwork is usually concealed and routed through the wall or directly outside.









Chimney-style hood
This designer model is fast gaining in popularity. Wall-mount hoods are installed directly on the wall and are usually ducted. When venting through ducts is not feasible, there are models available with a recirculation system.














Island-mount hood
This hood model is suspended above a kitchen island or peninsula and includes a chimney which can be adjusted according to the height of the ceiling. The fan can be either internal or external and vented through ductwork. When exterior ventilation is not feasible, some manufacturers offer ductless recirculation models. This type of range hood is excellent at funnelling away foul air from your kitchen since it is suspended without walls or cabinets to obstruct air circulation. It is therefore important to correctly evaluate the power of this type of hood.














Built-in hood
A built-in hood is designed to be installed in a custom-built cabinet. The ventilation module can be installed inside (internal module) or on the outside (external module). Models with exterior ventilation modules are quieter. Built-in hoods are high-performance with a ventilation capacity of between 600 and 1200 CFM. In situations where it is impossible to install a ducted system, some manufacturers offer recirculation models with charcoal filters.











Microwave with integrated hood
This is a microwave oven and range hood combined in one unit, installed over a cooktop. The fan is situated on the bottom of the microwave, and sucks up the air rising from the cooktop below. Air is either vented outside or filtered and recirculated back to the room. This type of inhaling hood takes up a lot less space in the kitchen than most other hood models.

Downdraft range hoods

A retractable downdraft system can be ideal when the cooktop is installed in a kitchen island or peninsula. It can also be installed behind most cooktops. Downdraft range hoods are located at the side or behind the cooking area and level with the cooking surface. The downdraft vent retracts down into the cabinet when not in use, and rises when in use. These models, practical because they are camouflaged, require an internal or external vent. They can be less effective than other types of hoods, since heat and foul air tend to rise, and, in certain cases, ventilation modules are too removed from some cooktop elements.

Slide-out range hoods

These models are installed under a kitchen cabinet with either outside venting or a recirculating charcoal filter. When not in use, the hood slides back nearly flush with the front of the cabinet, and when in use, it is pulled forward. Since only the drawer under the cabinet is visible, there is very little impact on the kitchen design.

Motor power

Range hoods are equipped with electric motors with varying capacity. This capacity is the amount of air and exhaust that a hood can ventilate and is measured in cubic feet per minute (CFM). This measurement, which only applies to exterior venting systems, is important when calculating the power required for a new kitchen range hood. When you calculate capacity, you should take kitchen volume and duct length into consideration. If you have an open-concept kitchen, you need to calculate the total volume.

In order to choose the best range hood for your kitchen, it is important to carefully evaluate the size of the environment in which it will be installed, and then choose a hood with suitable ventilation capacity with respect to the volume of the room. The hood should be capable of achieving 10 to 12 air changes per hour to adequately extract odours and fumes from the kitchen.

To calculate the required capacity, multiply the height (H) of the kitchen by its surface area (W x D), which will give you the volume of the room. Multiply this number by 10 and the result is expressed in m3/h. For example, in a room measuring 15m2 and 3m high, a hood with 450m3/h motor power should be installed.

You should also take duct length into account. A long duct with several 900 elbows requires extra ventilation capacity. The following table will enable you to evaluate minimum capacity requirements according to duct length:


Sizing
The width of most range hoods varies between 24 and 36". 30" models are the most popular since their width conforms to the width of most electric and gas stoves. As a general rule, the range hood should overlap the cooking surface by three inches on both sides (this increases the hood’s capturing area). This is particularly important for gas ranges.

Depth can vary slightly from one manufacturer to another and from one model to another. Hood depth should generally be calculated to overhang at least a half of the front elements.

Controls
Controls should be easy to reach, read and use. Among the different types of controls: rotary knobs or mechanical pushbuttons, electronic touch controls, glass-concealed touch buttons, LCD screens, and remote controls, which are very practical when the hood is very high or less accessible to people with reduced mobility. Controls can be located at the front of the hood, accessible underneath, or on the hood. There are usually three fan speeds to choose from, and a Boost mode.

Lighting
Most range hoods are equipped with one or more lights which provide an extra source of lighting in the kitchen. Lighting should be conceived to illuminate the work surface without blinding the user. Intensity can be controlled either mechanically or electronically at one, two, or three settings. Depending on the model chosen, you may have up to three incandescent, fluorescent or halogen bulbs. A few models include LED lighting, which is heat sensitive and generally not recommended.

Fans
Fans are made of plastic or metal and are generally located in the body of the range hood, making them easier to access for cleaning and maintenance, but also noisier. If you want to eliminate as much noise as possible, you should consider range hoods with fans placed outside the house. For this type of installation, intended solely for external venting hoods, the fan/motor casing is located in either the attic or roof space. Although a little more complex, this type of installation is much quieter. Motors are equipped with one of two types of fans, either:
• a propeller fan, with blades that move the air somewhat like the propeller of a plane, or;
• a centrifugal or blower fan, which resembles a hamster wheel, powered by a rotating cylinder with straight blades. This type of fan is more efficient and quieter than the propeller fan.

The air exhaust system in a kitchen usually consists of a fan and motor in the range hood. Other systems are available, such as those with in-line fans located in the ductwork routed out an exterior wall, or again those that operate with a fan located outside the house.

When noise is a prime consideration, check out models equipped with in-line fans or fans placed outside the home. A sone is a linear measure of noise loudness. It ranks and compares sounds as the ear hears them. One sone is about as loud as the noise made by a quiet refrigerator. A normal conversation takes place at about four sones, and at the other end of the spectrum, an airplane landing can exceed 250 sones. The sone rating for a range hood usually, but not always, reflects the fan speed at its highest setting.

Filters
The primary role of filters is to capture grease particles before they enter the ducting. Grease represents a potential fire hazard and can also present long-term cleaning problems. Rectangular or circular, filters come in various sizes depending on the hood model. Some models use two filters.

Three types of filter

Aluminum filters: Metal mesh filters or fine mesh filters are the most widely used. They can be removed easily, washed in the dishwasher and are therefore reusable. They consist of a sheet of aluminum mesh in a stainless steel frame. Effectiveness is determined by mesh size: the larger the mesh, the more likely grease will penetrate the ducting. Where they are available, fine-mesh aluminum filters are recommended.














Baffle filters: These commercial-style filters are made of stainless steel and placed inside the casing. More durable than aluminum filters, they cover the entire surface under the hood and can be washed in the dishwasher.















Charcoal filters: Charcoal filters and charcoal filter modules are used for ductless hoods. They eliminate cooking odours and capture grease. Modules are inserted in the hood; they are rarely interchangeable between hood models, except perhaps between models from the same manufacturer. They cannot be washed and must be replaced regularly.












Hood body
The hood body houses the various elements included in the hood, such as the filters, fan and motor. It can be made of painted steel, often black or white, stainless steel or even glass. For hoods ducted outside the home, there should be an opening of the appropriate size in the hood body. The body is generally finished to combine with other appliances in the kitchen.

Other features
Some hoods feature electronic touch controls for automatic shutoff functions and heat sensors that automatically increase fan speed and sound an alarm if things get too hot. Certain models are equipped with an electronic sensor which will automatically activate the hood when smoke is detected, even smoke from a cigarette. The intensity of the smoke in the air determines the suction power of the hood which will also turn off automatically.

Hoods with perimeter suction have recently come on the market; originally developed for commercial purposes, they capture peripheral odours and smoke very effectively. Heat SentryMC is a heat detector function that automatically adjusts the ventilation setting if the heat detected from the stovetop is too high.

Once the ventilation ducts are in place, the installation of the range hood is relatively simple. The height, or the distance between the range and range hood, varies according to the type of cooktop, suction and exhaust capacity, and the type of unit. As a general rule, the closer the hood is to the cooking surface, the more effective the evacuation of foul air will be.

Lower-performing (lower-capacity) hoods should be installed 18" to 24" from the cooktop.

Average-performing (medium-capacity) hoods should be installed 24" to 30" from the cooktop.

Top-performing (high-capacity) and commercial-type hoods should be positioned 30" to 36" from the cooktop.

These are general guidelines and will vary according to individual manufacturers. Be sure to read the instructions carefully.


Some advice:

• If the new range hood is a replacement, be aware that the location of the exhaust opening may vary from one manufacturer to another.
• The circumference of the ducting must be the same or greater than that of the connection located on the hood.
• A range hood should be installed a minimum of 20" above an electric unit and 30" above a gas range. For optimum efficiency, the distance between the cooking surface and hood should not exceed 30".
• Make the ductwork run as short and as straight as possible and with as few turns as possible; the more bends a duct has to make, the less effective the fan will be. When this is not possible, remember that 45° angles allow for better air circulation than 90° angles. Don’t forget to terminate with a roof cap or wall cap.
• With 6" round ducting, install a transition piece and seal joints with 2" duct tape. For optimum ventilation performance, install a 3 1/4" × 10" transition piece. The wall duct should be prepared for the adaptor that should be inserted easily into the duct.
• Never terminate venting into an attic. Excess moisture will damage wood structures and drywall. Furthermore, expelled cooking grease can create a fire hazard and will attract unwanted insects.
• Always use rigid steel ducts. Flexible duct pipe or corrugated metal are more prone to grease build-up, which can present a fire hazard.

Whatever installation method you choose, it is generally wise to consult an electrician. If you decide to do the installation yourself and to connect the range hood to an existing electrical circuit, remember the 15- amp rule, whereby the total load on any circuit breaker may not exceed 15 amps. If the range hood’s additional amperage plus existing elements (other appliances, lights, etc.) totals more than 15 amps, you’ll need to wire it into an empty breaker slot in the main panel. The optimum amperage (light and fan speed settings) will be indicated on a label attached to the hood. The Building Code requires that you install a junction box at every wire junction.

Remember that all electrical installations in Quebec must be carried out by a master electrician and member of the Corporation des maîtres électriciens du Québec (CMEQ).

Before purchasing, run your hand lightly over the surface of the hood to make sure there are no rough or sharp edges that could cause any injuries when you’re cleaning. Grease and soot accumulates in the filters, on the surface of the hood and on ducts. If you let filters become obstructed, their effectiveness will be compromised.

Maintenance should be carried out as follows:

• Soak aluminum mesh filters in soapy water or put them in the dishwasher to break down accumulated grease;
• Clean all surfaces with a mild detergent, and at least once a month if you fry a lot of food;
• Replace charcoal filters 2 to 4 times per year depending on how often the hood is used;
• Clean the fan blades. In many centrifugal fan models, these easy-to-remove blades can be put in the dishwasher.