Kitchen range hoods

In the kitchen, smoke, humidity, various smells, not always wholesome, and grease from the frying pan are but a few of the products that make it from the stove into the air. They can be a problem, more so in the winter when our homes are sealed off from the cold outside air. Some can be downright dangerous, for example, the smoke from charred meat that is known to contain carcinogens. Fortunately, a kitchen range hood is designed to purify and re-circulate the air (ductless) or to simply expel the offending products to the outside (ducted).

Before buying a range hood, consider the following items, (in no particular order of importance): Performance, Noise, Colour and style, Cleaning and Lighting.
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A few terms you’ll need to know
Models
Characteristics
Accessories
Cleaning
Backdrafts
Warranties

A few terms you’ll need to know

CFM is the acronym for cubic feet per minute. In this case, it’s used to measure the volume of air that is forced through the system by the fan and it becomes very important when, in a ducted system, one is calculating the force needed to propel the waste air through the vent to the outside. In fact, CFM is only measured in a ducted installation.

A sone is a linear measure of noise loudness. It ranks and compares the loudness of sounds on a common basis 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, a landing airplane can exceed 250 sones. Two sones are twice as loud as one, four sones twice as loud as two… For a range hood, the sone rating is usually, but not always, shown at the highest fan speed.
Over the years, range hoods have evolved along with kitchen design and layout from the classic wall-mounted model, to models installed adjacent to kitchen island cooking surface, to others concealed discretely under the kitchen cabinets. Types can be classified in a number of ways as shown in the following:
Fan types
Range hoods employ a variety of small electric motors depending on the desired CFM output. In most cases, these motors are equipped with one of two types of fans, either:
  • The blade fan (a.k.a. rotary fan, impeller fan) that resembles the propeller on a boat motor.
  • The centrifugal fan (blower fan, squirrel cage) that’s powered by a rotating barrel-shaped cylinder, with straight blades around the edge, and resembling an airplane turbine engine. Centrifugal fans are more efficient and quieter than blade fans.

Fans are made of plastic or metal. Most fans are located inside the body of the range hood, a feature that makes them more accessible for cleaning and maintenance, but also noisier. If noise is a prime consideration, check out models equipped with in-line fans or fans placed outside the house at the exhaust vent.
Ductless/ducted
  • Ductless models use charcoal filters to clean the air that is then returned to the room. They are simple to install (see Installation below) and capable of ridding the air of most grease and odours, but are considered less effective than ducted models as they return smoke, heat and humidity back into the room.
  • Ducted models expel the waste air to the outside through ducts. They are more demanding at installation time and, depending on the location of the range, may require carpentry and tinsmith tools and skills. On the other hand, they are more efficient, as they assure the complete elimination of waste air. Since air has to travel further in ducted models, be sure to buy a unit with adequate CFMs. Use the following suggestions:
Duct lengthCFM’s
1 to 15 feetup to 270
16 to 20 feet270 to 400
20 feet +400 or more
Of course, the above duct length to CFM ratio depends on the size of the ducts you install.
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