How Is Kitchen Ventilation Designed for C-Store Foodservice?

The engineer starts with the equipment schedule: every fryer, griddle, broiler, oven, and warmer listed with its duty classification. Grease-producing appliances get Type I hoods with listed baffle filters; the hood length covers the equipment plus the code-required overhang on the open sides, and the exhaust rate follows the hood manufacturer's listing for that appliance duty — not a generic cfm-per-foot guess. Capture depends on more than the fan size. The engineer checks the hood's mounting height, keeps supply diffusers from blowing across the hood face and disrupting capture, and verifies the kitchen's air balance so cross-drafts do not push cooking effluent past the filters. The fire suppression system — wet-chemical nozzles under the hood, tied to the fuel shutoff for gas appliances — is coordinated on the same drawings so the suppression piping, the hood, and the ductwork are one reviewed assembly.

Makeup air is sized to the exhaust total minus the small transfer air the design intentionally pulls from the sales floor — typically 80 to 90 percent of the exhaust volume, tempered to near room temperature. The dedicated makeup air unit gets its own gas or electric heat and, in humid climates, cooling or at least dehumidification consideration; dumping untempered makeup air into the kitchen destroys comfort and can condense moisture on cool surfaces. The grease duct is routed as directly as practical: vertical through the roof is preferred over long horizontal runs, because every horizontal foot is a grease-collection and fire-risk foot. The engineer details the welded liquid-tight construction, the clearance or listed enclosure system, cleanouts at each elbow and at code-required intervals, and the rooftop fan with a hinged, grease-rated upblast design. Termination clearances — from the canopy, from outdoor-air intakes, from property lines — are checked against the mechanical code before the curb is set.

Coordinate these with the health department and mechanical inspector: • Every cooking appliance classified; Type I vs Type II hood assigned per appliance duty • Hood sized with proper overhang; exhaust rate per the hood listing, not a rule of thumb • Tempered makeup air unit sized to 80-90 percent of exhaust; kitchen near neutral pressure • Supply diffusers located so they do not disrupt hood capture • Grease duct: welded liquid-tight, proper clearances or listed system, cleanouts at direction changes • Rooftop upblast fan with termination clearances from intakes, canopy, and property lines • Fire suppression nozzles coordinated with hood, duct, and gas-appliance fuel shutoff • Roof curb and flashing detailed to preserve the roofing warranty