Kitchen Stove Ventilation: Exhaust Hoods, Fans, and Filters

In homes and apartment units, there are a few kitchen items that are seldom appreciated until they are gone or out of order. These items are the stove hood, exhaust fan and exhaust filters.

Exhaust Hoods

The best way to keep a kitchen ventilated is with an exhaust hood located directly over the range and exhausting to the outdoors. Ideally, the hood will cover all of the burners and be no more than 26 inches above the range top. A higher location means a diminishing ability of the hood to capture rising fumes. The minimum requirement is at least 40 cubic feet per minute (cfm) capacity for each linear foot of hood length. For example, a 4-foot long hood should have a fan with a capacity of at least 160 cfm (4 times 40).

Ventless Stove Hoods and Exhaust Fans

The alternative is the use of a ventless hood, though they are less efficient than direct exhaust to the outdoors. Many of these hoods are found in apartments and homes with kitchens located away from an immediate outside wall. Ventless hoods can only remove smoke and grease and can not rid the kitchen area of heat or moisture. The quality of this type of hood depends on grease-filter efficiency and its fan air-handling cfm.

Exhaust Fan Fiters

The larger and thicker the filter, the better the ventless system will work. When purchasing new exhaust fan filters, compare the size and thickness between brands. Also compare the cfm rating of the filter. Some ventless exhaust hoods contain special filters designed to remove cooking odors. One particular type of filter known to work well is charcoal-activated. Ideally, such a filter should contain 2 to3 pounds of activated charcoal. This amount normally lasts up to 2 years before replacement is necessary.

Stove Hood and Exhaust Logistics

Considering the cost of installing ductwork to the outside of the house, the ventless hood has an advantage. However, if either hood exhaust system isn't performing as expected, check the movement of the air being drawn into the hood. The air should sweep across the range top before being drawn up into the hood. There should be no open windows or open doors near the range. The fan will then draw the air in around the cooking pots and pans pulling the heat and odors up and directly into the exhaust fan.

An exhaust hood can draw as much as 85 percent of cooking fumes. A hoodless model exhaust fan alone is only capable of up to 50 percent. The percentage of course, may vary depending on the size and design of the fan. Figure the total air volume in the kitchen in cubic feet and divide by 4 to determine the fan size required in cfm. Check the local hardware store or home center for a selection of vented or ventless models that would best fill the need.

Remember, always work safely.