The Appliance Most Kitchens Get Wrong
Range hoods are one of the most commonly undersized and poorly positioned appliances in residential kitchens. Many are chosen primarily for aesthetics — the sweep of stainless steel, the design profile — without reference to whether they have adequate capture velocity, sufficient CFM for the cooking surface below, or ducting that actually vents to the exterior.
A range hood that doesn’t do its job — and many don’t — allows cooking grease, steam, combustion byproducts (from gas ranges), and cooking odors to distribute through the home rather than being captured at the source. Over time this deposits grease on cabinetry, discolors walls, and in the case of gas cooking, introduces combustion byproducts into the home’s air.
CFM Requirements: What the Numbers Actually Mean
Range hood capacity is rated in CFM (cubic feet per minute of air moved). The required CFM depends on the cooktop’s BTU output for gas, or the size of the cooking surface for electric. A general rule for gas: 100 CFM per 10,000 BTU of total cooktop output. A standard 4-burner residential gas range with 40,000 total BTU needs at least 400 CFM of hood capacity.
Most residential range hoods sold for residential use are rated between 200 and 600 CFM. Budget hoods with 200 CFM ratings are adequate for apartment cooking with low-BTU burners; they’re inadequate for any serious cooking on a full-output gas range. The CFM displayed on packaging is also maximum capacity under zero static pressure conditions — actual delivered CFM through duct runs is lower.
Ducted vs. Recirculating: The Difference That Matters Most
A ducted (externally vented) range hood pulls air out of the kitchen and exhausts it outside the building. A recirculating (ductless) hood pulls air through a charcoal filter and returns it to the kitchen. The difference in performance is enormous and rarely acknowledged in hood marketing.
Recirculating hoods remove some grease particles and some odors but cannot remove heat, steam, humidity, or combustion byproducts from gas cooking — these return to the kitchen air with the filtered air. Ducted hoods remove all of these. For serious cooking — particularly on high-output gas ranges — recirculating hoods are a significant compromise. Install a ducted system whenever the path to exterior is feasible; use recirculating only when exterior ducting is physically impossible.
Hood Position and Capture Efficiency
A range hood positioned too high above the cooking surface captures poorly because cooking plumes expand as they rise — the wider the plume at capture, the more escapes the hood perimeter. The standard recommendation is 18–24 inches above electric cooktops and 24–30 inches above gas (slightly higher for gas to reduce heat exposure to the hood).
Hood width matters too: the hood should be at least as wide as the cooking surface, and ideally 3 inches wider on each side for wall-mounted installations, or 6 inches wider on each side for island hoods (where the plume is more vulnerable to cross drafts). Undersized hoods look balanced but allow the edge burners’ output to escape around the perimeter.
Makeup Air: The Problem High-CFM Hoods Create in Tight Houses
Modern well-sealed homes can have a significant airflow problem when a high-CFM range hood runs. The hood exhausts a large volume of air rapidly; if the house is sealed tightly enough, this creates negative pressure that impedes the hood’s own performance, back-drafts combustion appliances (furnaces, water heaters, fireplaces), and can cause uncomfortable pressure sensations.
High-CFM hoods (600+ CFM) in well-sealed homes typically require a makeup air system — a supply of outside air introduced to the kitchen to compensate for what the hood exhausts. This is a code requirement in some jurisdictions for hoods above certain CFM thresholds. It’s an often-overlooked design element when specifying high-performance kitchen ventilation.