Common Problems in Central Kitchen Exhaust Systems and How to Fix Them

In Singapore’s fast-paced food industry, central kitchens have become essential for large-scale meal production, catering services, and restaurant chains. But as these kitchens handle high cooking volumes daily, their exhaust systems face heavy wear and tear. Over time, even the most advanced exhaust setups can develop issues that compromise efficiency, hygiene, and safety.

Recognising and addressing these problems early can save your business from costly repairs, downtime, or even fire hazards. This article explores the most common problems in central kitchen exhaust systems and practical steps to fix or prevent them — ensuring smooth, compliant, and safe kitchen operations.

1. Excessive Grease Buildup Inside Ducts and Hoods

The Problem

Grease accumulation is by far the most common issue in any kitchen exhaust system. During cooking, oil and grease vapours rise into the hoods, where they condense and stick to filters, ducts, and fans. Over time, this buildup forms thick, sticky layers that:

• Reduce airflow efficiency

• Increase the risk of fire

• Create unpleasant odours

• Violate NEA and SCDF hygiene standards

In central kitchens — where multiple cooking stations operate at once — this problem escalates quickly.

The Fix

• Regular Cleaning Schedule: Engage professional duct cleaning services at least every 3–6 months, depending on kitchen usage.

• Install High-Efficiency Baffle Filters: These trap grease droplets before they enter the ducting.

• Use Fire-Rated Grease Ducts: These materials resist ignition even if grease catches fire.

• Implement Access Panels: Easy access allows technicians to clean ducts more thoroughly.

Proper maintenance not only prevents fire hazards but also keeps your exhaust running efficiently for years.

2. Weak Suction or Poor Ventilation

The Problem

If staff notice that smoke, heat, or odours linger in the kitchen longer than usual, it’s a sign of weak suction. In central kitchens, poor ventilation can lead to overheating, discomfort, and non-compliance with safety codes.

Common causes include:

• Blocked filters or duct obstructions

• Worn-out fan belts or impellers

• Undersized exhaust fans

• Damaged duct joints causing air leaks

The Fix

• Inspect Filters Weekly: Wash or replace grease filters regularly to prevent clogs.

• Check for Air Leaks: Ensure all joints and connections are properly sealed.

• Upgrade Fan Capacity: If airflow demand has increased due to new cooking stations, you may need a higher-capacity fan.

• Balance Airflow: Use airflow meters to ensure consistent suction across all hoods.

Professional testing and airflow balancing ensure your system meets the optimal cubic metre per hour (CMH) extraction rate for each cooking zone.

3. Noisy or Vibrating Exhaust Fans

The Problem

Noise and vibration in exhaust fans are more than just annoyances — they indicate underlying mechanical or installation issues. Persistent vibration can lead to fan motor wear, loose mounts, and even structural damage to ducts or ceilings.

Common causes:

• Loose fan blades or bolts

• Misaligned motor shafts

• Imbalanced impellers

• Poor vibration isolation during installation

The Fix

• Tighten All Fasteners: Regularly check and secure bolts and fan housings.

• Install Anti-Vibration Mounts: Rubber or spring isolators can absorb mechanical noise.

• Balance Fan Blades: Professional technicians can rebalance impellers to prevent uneven rotation.

• Schedule Regular Servicing: Preventive maintenance identifies potential motor issues before they worsen.

Quiet exhaust systems not only enhance working conditions but also demonstrate proper engineering and care.

4. Water Leakage or Condensation Issues

The Problem

Central kitchens generate large amounts of heat and moisture, especially during long hours of operation. If ducting is poorly insulated or improperly sloped, condensation can form inside and drip back into the kitchen. In severe cases, you may notice:

• Water stains around hoods

• Leaks onto cooking areas

• Corrosion in ducts or ceiling panels

This problem is common in Singapore’s humid climate, where temperature differences between indoor and outdoor air amplify condensation.

The Fix

• Install Proper Insulation: Use thermal insulation on ducts that pass through air-conditioned or cold spaces.

• Ensure Proper Drainage: Ducts should have slight slopes directing condensation to drain points.

• Use Double-Walled Ducts: These reduce temperature differences and minimise condensation.

• Inspect Regularly: Catch early signs of water pooling before corrosion begins.

Fixing condensation not only protects your kitchen but also prevents bacterial growth and hygiene issues.

5. Odour Problems and Smoke Recirculation

The Problem

If strong cooking smells linger in your kitchen or escape into neighbouring units, it’s a clear indication that your exhaust system isn’t effectively removing odours or smoke. This is especially problematic in multi-tenant buildings or shared facilities.

Causes include:

• Ineffective filtration

• Damaged duct seals allowing smoke to leak

• Improper discharge height or direction

• Blocked airflow due to dirty ESPs or carbon filters

The Fix

• Install Odour Control Devices: Electrostatic precipitators (ESPs), UV ozone systems, or activated carbon filters can neutralise smoke and smells.

• Check Ductwork for Leaks: Ensure airtight seals throughout the system.

• Comply with NEA Discharge Rules: Exhaust outlets should be at least 1 metre above roof level or 6 metres from air intakes.

• Clean ESPs Monthly: These devices lose efficiency when layers of grease and soot accumulate.

With proper odour control, your central kitchen remains compliant and neighbour-friendly — an important factor in Singapore’s dense urban landscape.

6. Negative Air Pressure in the Kitchen

The Problem

A well-balanced kitchen should have slightly negative air pressure to prevent odours from escaping, but too much negative pressure can cause multiple issues:

• Difficulty opening doors

• Backdrafting of smoke into the kitchen

• Disruption of gas burner flames

• Staff discomfort due to air imbalance

This often happens when the exhaust system removes more air than is replaced by make-up air systems.

The Fix

• Install a Make-Up Air System: Introduce filtered and tempered air to balance the exhaust rate.

• Adjust Fan Speed Controls: Use variable speed drives (VSDs) to regulate airflow.

• Inspect Building Ventilation: Ensure your central kitchen’s system integrates properly with the building’s HVAC design.

Balancing airflow ensures safer operations and more comfortable working conditions for staff.

7. Grease Leakage Around Hood or Duct Joints

The Problem

When grease escapes from duct joints or hood seams, it leaves oily stains and a sticky residue around the kitchen. Apart from being unsightly, it indicates potential leakage points that can compromise the system’s efficiency and fire safety.

The Fix

• Seal All Duct Joints Properly: Use high-temperature silicone sealant or welded seams to ensure airtight connections.

• Install Grease Troughs: These catch drips from filters and prevent them from falling onto food or equipment.

• Replace Damaged Filters: Worn filters allow more grease to bypass into the ducts.

Leaks must be fixed promptly, as accumulated grease on external surfaces can attract pests and violate hygiene standards.

8. Frequent Fan Motor Failures

The Problem

Exhaust fans are the workhorses of your ventilation system. If motors frequently fail, it’s usually a symptom of electrical overload, poor maintenance, or overheating. In central kitchens, where exhaust fans often run continuously, even small inefficiencies can shorten their lifespan.

The Fix

• Lubricate Bearings Regularly: Reduces friction and prevents overheating.

• Ensure Proper Voltage Supply: Fluctuations can damage motor windings.

• Clean Fan Blades: Accumulated grease adds weight, forcing the motor to work harder.

• Install Thermal Overload Protection: Automatically shuts down the motor before overheating occurs.

Choosing industrial-grade, continuously rated motors also improves reliability in high-usage kitchens.

9. Corrosion and Metal Fatigue

The Problem

Moisture, cleaning chemicals, and grease vapour can cause corrosion in ducts, hoods, and fan housings. Over time, corroded metal weakens, leading to leaks, noise, and system inefficiency.

The Fix

• Use Stainless Steel Ducts: Prefer grade 304 or 316 for high humidity and grease environments.

• Apply Protective Coatings: Anti-corrosion coatings can extend the lifespan of ducts and fans.

• Regular Inspections: Identify early signs of rust, especially around joints and fan blades.

Replacing corroded sections promptly prevents further damage and costly system overhauls.

10. Clogged or Damaged Filters

The Problem

Filters play a vital role in capturing grease and particulates. However, when neglected, they clog and restrict airflow. This forces fans to work harder, reduces efficiency, and can even lead to overheating or motor burnout.

The Fix

• Clean Filters Weekly: Most stainless steel baffle filters can be washed with hot water and detergent.

• Inspect for Damage: Replace filters with bent fins or worn frames.

• Upgrade to High-Efficiency Models: Some filters are designed for better capture and lower resistance.

Clean filters not only maintain suction performance but also prevent unpleasant odours and fire risks.

11. Inadequate Maintenance and Lack of Records

The Problem

Many central kitchens neglect proper documentation of their exhaust system maintenance. This becomes a major issue during NEA or SCDF inspections, which require proof of regular servicing and cleaning.

The Fix

• Create a Maintenance Logbook: Record each cleaning, inspection, and service.

• Engage Licensed Contractors: Only certified professionals should handle duct cleaning and fire safety systems.

• Schedule Routine Inspections: Monthly visual checks and quarterly deep cleans keep your system compliant.

A documented maintenance record not only demonstrates compliance but also improves accountability and safety.

12. Electrical and Control System Failures

The Problem

Modern kitchen exhaust systems often include sensors, automated controls, and interlinked fire suppression systems. When these fail due to wiring faults or software errors, ventilation performance suffers.

The Fix

• Conduct Electrical Safety Inspections: Ensure grounding and wiring integrity.

• Check Control Panels: Reset or replace faulty sensors and relays.

• Integrate with Fire Systems Properly: Exhaust systems should automatically shut down during fire activation.

Working with experienced technicians ensures all systems remain operational and compliant with local codes.

13. How to Prevent Problems Before They Start

Prevention is always better than cure. Implementing a proactive maintenance plan is the best way to keep your exhaust system performing optimally.

Preventive Measures:

1. Schedule professional cleaning every 3–6 months.

2. Inspect hoods and ducts monthly for grease or leaks.

3. Replace worn-out filters promptly.

4. Balance airflow regularly to ensure uniform suction.

5. Train staff to report unusual noises, smells, or leaks early.

By integrating maintenance into your operations, you avoid expensive repairs and unexpected shutdowns.

14. Partnering with a Reliable Exhaust Specialist

No matter how well-built your system is, you’ll eventually need professional help for inspection, cleaning, or redesign. Working with a trusted commercial kitchen exhaust specialist ensures all maintenance and repairs are done safely, correctly, and in accordance with Singapore’s NEA and SCDF regulations.

A reliable partner offers:

• Customised cleaning and service schedules

• Thorough duct inspections with reports

• Replacement parts for fans, filters, and motors

• NEA/SCDF compliance documentation

Professional expertise keeps your system functioning efficiently and your operations worry-free.

15. Conclusion: Keep Your Kitchen Safe, Efficient, and Compliant

Your central kitchen exhaust system works tirelessly behind the scenes — managing heat, smoke, and grease so your chefs can focus on creating great food. But when neglected, small issues can escalate into major safety hazards and operational setbacks.

By recognising common problems such as grease buildup, weak ventilation, or odour leakage — and fixing them early — you not only protect your investment but also ensure the health, safety, and productivity of your staff.

Regular maintenance, professional servicing, and smart design upgrades will keep your system performing at its best year after year.

To learn more about professional installation, inspection, and maintenance services for central kitchen exhaust systems in Singapore,
visit https://commercialkitchenexhaust.sg/.