Range hoods contribute to a healthy home

By removing the by-products of cooking and combustion at the source, range hoods minimize the concentration of particulate matter, nitrogen dioxide and other pollutants in your home. They also reduce odors and moisture.

Studies show that many homes use exhaust fans that move too little air. The worst ones just recirculate the air through filters. All range hoods should vent to the outdoors. Hoods are designed to mount under cabinets, on walls or over islands. Downdraft systems work close to the cooktop.

The amount of airflow you need, expressed in cubic feet per minute (cfm), depends on several factors. The Home Ventilation Institute (HVI) recommends 100 cfm of airflow per linear foot of range, or 150 cfm for an island range. So a standard 30-in. range calls for a 250- or 375-cfm hood. A downdraft system may require more airflow.

Actual performance varies widely. Look for units certified by the Home Ventilation Institute, which verifies that they meet the stated ratings for airflow, sound and energy use. HVI also offers a searchable database for making comparisons.

Be careful not to oversize the fan, which can lead to backdrafting. This occurs when negative pressure in the house causes the airflow through fireplaces, water heaters or other combustion appliances to reverse. If you want a high-capacity fan to ventilate your range-top barbecue, match it to a supply of makeup air to keep the house pressure in balance.

Fan noise is an important consideration. Once you find the size and style you want, buy the quietest unit you can afford. The hood should also be easy to clean. Filters are either aluminum-mesh panels or restaurant-style baffles. Both are dishwasher-safe. Some units let you remove the fan’s impeller (squirrel cage) for cleaning. That’s a good time to inspect the backdraft louver. It should be clean and pivot freely.