What you need to know about range hoods

Choosing a new range hood can be almost as daunting as choosing the range itself. Arm yourself with the knowledge you need to make the right decision for your range — and your lifestyle.

• Range hoods are venting devices designed to remove cooking odours, moisture, grease and smoke from the kitchen area.
• Most range hoods have a light and a fan that sucks up air and carries it out of the house through a duct.
• Non-circulating range hoods (often used in apartment buildings) filter out odours and moisture but don't vent used air outdoors.
• Range hoods function as important fire breaks between the range and cabinets above. The hood is a physical barrier while the operating fan constantly dilutes heat.
• Ducted hoods remove cooking odours and are especially important in newer, well-sealed, energy-efficient homes.

• As a rule, range hoods should be large enough to cover the whole cooktop. Especially with commercial ranges, the range should extend three inches beyond both sides.
• They're usually installed about two feet above the cooktop, but the exact height depends on the model.
• Manufacturers specify the recommended size for the ductwork that the hood vents into. While you may be able to use larger ducts than recommended, you should never use smaller ones.

• Range hoods are rated according to the noise they make and the amount of air they move. The greater the heat produced by an appliance, the greater the air movement required.
• Blower noise is measured in sones. One sone is approximately the amount of noise made by a typical refrigerator. Your average range hood fans generate five to eight sones at maximum speed.
• Air movement is rated in cubic feet per minute (cfm). The amount of heat an appliance produces is stated in British thermal units (BTUs).
• A conventional range (producing about 36,000 BTUs) needs a blower with a cfm rating of 160 to 200.
• A commercial range or an indoor grill requires higher cfm ratings than a standard range hood.

• Hood blowers can be built into the range hood or installed separately nearer the point where air is exhausted outdoors.
• Moving the blower three metres (10 feet) away from the hood will reduce the noise level by about 25 percent.
• An alternative to a range hood is a down-draft vent, which is useful for a range that's part of a kitchen island or peninsula.
• Down-draft vents with intakes elevated above the appliance are more efficient than units flush with the burners.

Range hoods are an absolute necessity for keeping your kitchen safe and odourless. If you know what your home can handle, and what kind of appliances you have, the buying process can be much easier.