Restaurant duct systems move large volumes of air to remove smoke, grease, and heat from kitchens. Proper design keeps the dining environment comfortable and helps the kitchen run safely.
These ducts also support ventilation compliance and energy efficiency when sized and maintained correctly. The following sections break down the main components, performance factors, and upkeep practices.
| Component | Function | Typical Material | Key Sizing Factor |
|---|---|---|---|
| Hood | Captures grease and smoke at the source | Stainless steel | Capture velocity and kitchen volume |
| Ductwork | Transports contaminants to the exhaust point | Galvanized steel or aluminum | Duct diameter and layout length |
| Filter | Strips grease and fine particles | Aluminum baffle or synthetic media | Filter type and face velocity |
| Fan | Provides pressure to move air | Backward curved centrifugal | Total pressure and flow required |
| Makeup Air | Replaces exhausted air to stabilize pressure | Conditioned or tempered | CFM introduced relative to exhaust |
Design Considerations for Restaurant Exhaust Layout
Effective exhaust layout matches equipment placement to duct runs and hood types. Keep horizontal runs short and sloped toward the fan to limit grease buildup.
Use capture hoods above fryers and high-output cooking lines, while canopy hoods work best for wide cooking surfaces. Avoid long vertical rises that increase pressure drop and reduce fan efficiency.
Material Selection and Fire Safety
Choose noncombustible materials with smooth interior surfaces for the duct interior. Galvanized steel is common, while aluminum can be used in low-temperature zones.
Specify fire-rated insulation when ducts pass conditioned spaces, and follow clearance rules to combustible construction. Hangers and supports must match the insulation thickness and duct weight.
Performance Testing and Commissioning
After installation, test balance each kitchen zone and verify the fan delivers rated CFM at the design differential pressure. Check duct velocities to keep grease in suspension without excessive noise.
Document airflow readings, duct surface temperatures, and filter pressure drop. Establish baseline values so future changes are easy to detect and correct.
Maintenance Routines and Inspection Requirements
Scheduled cleaning of hoods, filters, and ducts reduces fire risk and sustains airflow. Frequency depends on cooking volume, filter type, and local code.
Professional duct cleaning removes accumulated grease from interior surfaces. Replace or clean panel and cassette filters on a fixed calendar to maintain capture efficiency.
Key Takeaways for Restaurant Duct Planning
- Match hood type to cooking equipment and local ventilation codes.
- Size ducts and fans based on total hood CFM and duct friction.
- Specify smooth, noncombustible materials and maintain fire clearances.
- Implement a routine cleaning and inspection schedule tied to usage levels.
- Monitor fan performance and airflow indicators to catch issues early.
FAQ
Reader questions
How often should restaurant ducts be professionally cleaned?
Cleaning intervals vary with cooking type and volume, but most commercial kitchens schedule duct cleaning every 3 to 6 months to meet fire code and maintain performance.
What signs indicate the fan is undersized or failing?
Look for lingering odors, slow smoke capture, condensation in the duct, or unusually high energy use, all of which can point to fan or airflow issues.
Can incorrect duct sizing affect indoor comfort and energy costs?
Yes, undersized ducts cause backdraft and pressure problems, while oversized ducts increase fan energy and noisiness without improving capture.
Are flexible duct connectors allowed in the main exhaust run?
Use short, UL-listed flexible connectors only where movement or vibration requires them, and keep long, unbraced flexible runs out of the primary exhaust path to avoid collapse and pressure loss.