Stainless gas range with burner grates under white cabinets and a hood

Generic photo: Curtis Adams · Pexels License

Choosing a range hood: CFM rule of thumb, hood width and mounting height

Rules of thumb used across the industry: for gas, about 100 CFM per 10,000 BTU of total burner output (total BTU divided by 100); for electric, about 100 CFM per linear foot of cooktop width (10 CFM per inch). Make the hood at least as wide as the cooktop, and wider (about 3 in each side) on gas and island installs. Mount it inside the height range in the hood's own installation instructions, because capture drops fast when a hood is mounted too high. Then check makeup air if the result is over 400 CFM.

Cross-checked ~20 min easyBrands: All

Before you start

Never mount a hood lower than the minimum height in its instructions; it is a fire clearance as well as a capture setting
Gas appliance work (moving or connecting the range) is licensed gas-tech work

Diagnostic steps

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Under the IRC kitchen makeup-air section (M1503.6 in recent editions, M1503.4 in 2009), a hood able to exhaust more than 400 CFM needs makeup air at roughly the same rate, with at least one damper that is gravity or motorized and opens automatically when the hood runs. Recent editions apply it only when the home has a fuel-burning appliance inside the air barrier that is neither direct-vent nor mechanically drafted (e.g., a natural-draft water heater or a wood fireplace). States and cities amend this, so the local code office decides. This guide is a pre-sale and diagnosis check, not an HVAC design.

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