Commercial Kitchen Exhaust Hoods

What Commercial Kitchen Exhaust Hoods Do

Commercial kitchen exhaust hoods are the capture end of a ventilation system: they collect the thermal plume rising off cooking appliances, separate grease, and pass the remaining air into the exhaust duct. A hood that is the right type, size and style keeps smoke out of the room, keeps grease out of the ductwork, and gives the fire suppression system a defined zone to protect.

The hood never works alone. It depends on an exhaust fan that pulls the design airflow, on make-up air that replaces what leaves the building, and on a duct that is sealed and routed correctly. When one of those parts is undersized or poorly placed, the hood spills, no matter how well it was built.

Every kitchen is reviewed by a plan reviewer, a mechanical inspector and usually a fire marshal. Designs are prepared with NFPA 96 and the locally adopted mechanical code in mind, and the authority having jurisdiction (AHJ) has the final say on what gets approved.

Type I and Type II: Two Hood Categories by What the Appliance Produces

The first decision for any hood is its type, and the type follows the appliance. Codes split kitchen hoods into two categories based on whether the cooking process releases grease or smoke.

A Type I grease hood is the right call whenever an appliance produces grease-laden vapor or smoke. A Type II hood handles heat, steam, condensate and odor. Some appliances, such as certain ovens, sit in a gray area, and the manufacturer data plus the AHJ decide. The full comparison lives in our Type 1 vs Type 2 guide.

Choosing a Hood Style for Your Cook Line

Hood style is set by where the cook line sits in the room. The same appliances can need noticeably different airflow depending on whether the hood is against a wall or hanging free, because open sides let cross drafts push the plume out of the capture zone.

Wall canopy

The most common layout. The back of the hood seals to a wall, which blocks drafts from behind and helps the plume rise into the filters. Wall canopies usually need the least exhaust air for a given appliance load.

Island canopy

Used when appliances stand in open floor space, such as display cooking or a center line. Single island hoods are open on all four sides, so they generally require more exhaust than a wall hood over the same equipment. Double island hoods cover two lines placed back to back.

Backshelf and proximity hoods

Low, compact hoods mounted close to counter-height appliances. They suit tight kitchens with light to medium duty equipment but have limits on appliance height and type.

Appliance duty class (light, medium, heavy or extra-heavy as described in ASHRAE 154) drives the exhaust rate for each style. Our hood sizing guide walks through length, depth and overhang.

What a Complete Hood Package Includes

A complete hood package is everything needed to turn a cook line into an approved, working ventilation system. When we quote, we list each item so contractors know exactly what is in scope and what is by others.

• Hood body: stainless steel canopy, filter bank, grease trough and removable grease cup.
• Grease filters: listed stainless baffle filters for Type I hoods.
• Lighting: enclosed, gasketed fixtures rated for hood use.
• Fire suppression: a UL 300 wet chemical system with nozzles, detection, manual pull station and fuel or power shutoff, typically installed by a licensed fire suppression contractor.
• Controls: fan switching, interlocks between exhaust and make-up air, and optional demand control ventilation.
• Exhaust fan: a fan suited to restaurant grease exhaust (UL 762 listed models are common) with hinge kit and grease containment.
• Grease duct: welded duct, access panels and clearance protection. See grease duct systems.
• Make-up air: tempered or untempered supply sized to balance the exhaust.

How We Run a Hood Project From Drawings to Startup

A hood project moves through four steps, and the order matters because each step feeds the next.

1. Review: we read the equipment schedule, kitchen plan and reflected ceiling plan, and confirm appliance types, fuel and dimensions.
2. Engineering: hood type, style, length and exhaust rate per section are set; duct route, fan and make-up air are sized together. Submittal drawings go to the design team and the AHJ.
3. Fabrication: hoods are built to the approved shop drawings, with filter banks, light openings and duct collars located to match the field.
4. Installation and startup: hoods are hung, ducts connected and welded, fans set, and airflow checked against design before the inspection.

Details on site work are on our hood installation page.

Getting an Accurate Hood Quote

The fastest way to an accurate quote is to send the drawings you already have. An equipment list with model numbers, a floor plan showing the cook line, ceiling height and the roof or wall where the duct will exit are usually enough to size the hood and price the system.

If the project is still at concept stage, a short call with an engineer can settle hood type and style before the architect locks the layout. You can request a quote or send plans and questions straight to an engineer.