Commercial Kitchen Exhaust System Design
Target Audience: Kitchen designers, restaurant owners, HVAC engineers, environmental compliance officers.
Summary: A complete guide to commercial kitchen exhaust systems covering system components, airflow calculation methods, grease filter selection, fan/duct design, installation standards, and environmental compliance requirements.
Summary: A complete guide to commercial kitchen exhaust systems covering system components, airflow calculation methods, grease filter selection, fan/duct design, installation standards, and environmental compliance requirements.
Commercial kitchen exhaust systems are critical infrastructure that directly impacts working conditions, food safety, and environmental compliance. Poor design leads to hot kitchens, grease backflow, excessive noise, and regulatory violations. This guide covers every aspect of exhaust system design from component selection to maintenance protocols.
1. System Components & Principles
A complete exhaust system consists of 6 core components:
| Component | Function | Location |
|---|---|---|
| Stainless Steel Hood | Capture cooking grease and heat | Directly above cooking surface, 26–30 in high |
| Grease Filter / Precipitator | Remove grease particles for emission compliance | Upstream of fan or outdoors |
| Centrifugal Exhaust Fan | Provide airflow动力, overcome duct resistance | End of duct run or outdoors |
| Ductwork | Transport grease-laden air to discharge | Hood → filter → fan → discharge |
| Silencer | Reduce fan operating noise | Fan outlet end |
| Fire Damper (280°C) | Auto-close on fire to block spread | Wall/floor penetrations |
2. Airflow Calculation Methods
Method 1: By Hood Area
Formula: Q = Hood Area (m²) × Face Velocity (m/s) × 3600
- Chinese kitchen face velocity: 0.5–0.8 m/s
- Western kitchen face velocity: 0.3–0.5 m/s
- Example: 4m² hood, 0.6 m/s → Q = 4 × 0.6 × 3600 = 8,640 m³/h
Method 2: By Kitchen Area
| Kitchen Type | Air Changes/Hr | Per m² Reference |
|---|---|---|
| Chinese kitchen (high-BTU wok) | 50–60 ACH | 100–120 m³/h per m² |
| Western kitchen | 30–40 ACH | 60–80 m³/h per m² |
| Cafeteria / fast food | 40–50 ACH | 80–100 m³/h per m² |
| Bakery / pastry | 20–30 ACH | 40–60 m³/h per m² |
Makeup Air Calculation
Makeup air = Exhaust air × 80%. Maintains slight negative pressure (-5 to -10 Pa) to prevent grease migration into dining areas.
3. Grease Filter / Precipitator Selection
| Type | Efficiency | Best For | Price (USD) | Pros / Cons |
|---|---|---|---|---|
| Electrostatic Precipitator | 90–98% | Mid-to-high-end restaurants | $1,100–$4,200 | High efficiency; monthly cleaning required |
| UV Photolysis | 85–95% | Odor-sensitive locations | $700–$2,100 | Removes odors; lamp replacement quarterly |
| Composite (ESP + UV) | 95–99% | Strict environmental zones | $2,100–$7,000 | Highest efficiency; highest investment |
| Mechanical Filter | 60–80% | Pre-treatment / auxiliary | $280–$700 | Low cost; moderate efficiency |
Selection Guidelines
- Capacity ≥ system exhaust volume (1.1–1.2x safety factor)
- Efficiency ≥ 95% (urban centers recommend 98%+)
- Service clearance: 20 in (500mm) before and after unit
4. Fan, Duct & Installation
| Component | Selection Criteria | Price (USD) |
|---|---|---|
| Centrifugal Fan | Match filter capacity, static pressure ≥800Pa | $420–$1,700 |
| Ductwork | Galvanized or SS, sized for 8–12 m/s velocity | $28–$70/ft |
| Silencer | Impedance composite, 15–25 dB reduction | $140–$560 |
| Makeup Air Unit | 80% of exhaust, filtered + heated | $700–$2,100 |
| Fire Damper (280°C) | Thermal auto-close at fire-rated penetrations | $70–$210 |
Maintenance Schedule
| Item | Frequency | Action |
|---|---|---|
| Hood cleaning | Weekly | Clean filters and interior grease |
| Precipitator cleaning | Monthly (1–2x) | Clean collector plates, check insulators |
| Fan inspection | Quarterly | Check impeller balance, bearing lubrication |
| Duct inspection | Semi-annually | Check seals and grease accumulation |
| Fire damper test | Quarterly | Test auto-close function |
5. FAQ
What are the system components?
Stainless steel hood, grease filter/precipitator, centrifugal exhaust fan, ductwork, silencer, and fire damper. The grease filter is the most critical component for emission compliance.
How to calculate exhaust airflow?
Q = Hood area × face velocity × 3600. Chinese kitchens: 0.5–0.8 m/s face velocity (100–120 m³/h per m²). Western kitchens: 0.3–0.5 m/s (60–80 m³/h per m²). Makeup air = exhaust × 80%.
How to select a grease filter?
Efficiency 95%+ (98%+ for urban areas). Choose electrostatic or composite (ESP+UV) type. Capacity ≥ exhaust volume × 1.1. Clean electrostatic units monthly for optimal performance.
How to reduce exhaust system noise?
1. Install silencer on fan outlet (15–25 dB reduction). 2. Mount fan outdoors or in mechanical room. 3. Flexible connections at wall penetrations. 4. Select low-noise centrifugal fans (≤65 dB). 5. Regular impeller balancing maintenance.
What is the exhaust system investment?
Small restaurant (320–540 sq ft kitchen): $2–5.5K. Medium (540–1,075 sq ft): $5.5–14K. Large kitchen (1,075+ sq ft): $14–42K. Includes hood, precipitator, fan, ductwork, and makeup air system.
6. About Fengzhida
Fengzhida is a professional commercial kitchen equipment manufacturer in Zhongshan, Guangdong, China, offering complete exhaust system solutions. OEM/ODM available. Learn more: Fengzhida Official Website.
Related: Kitchen Equipment List | Hotel Kitchen Setup | Seafood Kitchen
This article was originally published by Fengzhida Commercial Kitchen Equipment.