Spotting A Grease Leak In Your Exhaust Hood

Imagine starting your day in the kitchen, ready to serve customers, only to discover a brownish liquid dripping from your exhaust hood. Whether it’s a grease leak or leftover cleaning water, identifying the source quickly is critical for protecting your kitchen, staff, and equipment.

Commercial kitchen ventilation systems work hard every day. Over time, grease buildup, weld issues, or duct seams can cause grease leaks that require attention. Here’s how to identify the problem and what to do next, straight from the experts at HoodMart.

So You’ve Spotted a Leak: Here’s What to Do Next

The first step when you notice liquid dripping from your hood is determining whether it’s grease or water.

If your system was recently cleaned, the liquid may be water. During manufacturing, exhaust hood systems are welded to create a watertight seal. Before inspection approval, fire marshals often perform light testing to check for gaps in weld seams. If light passes through, the hood fails inspection and must be rewelded.

Even with inspection protocols, minor imperfections can occur. During duct cleaning, water may accumulate and seep through small gaps in the weld points in the days following service.

However, if the substance appears thick and slow-moving, you may be dealing with a grease leak instead of water.

Pinpointing the Source of a Grease Leak

Grease leaks typically result from weak welds, failing seams, or buildup inside the grease vent system.

You can identify a grease leak by:

• A thicker, sticky consistency compared to water
• A darker brown or yellow tint
• Slower movement when dripping
• Residue buildup near seams or joints

Start by examining weld points for weaknesses. If you cannot locate a compromised weld, inspect additional components such as:

• Access doors within the duct
• The ductwork itself
• The grease trough that collects runoff from filters
• The hood grease cup

A full hood grease cup can sometimes overflow, mimicking a grease vent leak. Regularly emptying and cleaning the grease cup helps prevent unnecessary buildup and dripping.

Other Signs Your Grease Vent System Needs Attention

In some cases, ventilation issues may present differently. For example, if you notice cold air coming through stove vent openings during colder months, it may indicate airflow imbalance or improper sealing in the grease vent system.

While not always directly tied to grease leaks, airflow irregularities can signal duct or damper concerns that should be evaluated. Properly functioning exhaust and makeup air systems help prevent pressure imbalances and reduce strain on your ventilation components.

Routine inspection and maintenance go a long way in preventing both grease leaks and airflow issues.

Why You Should Always Consult a Professional

Whether you suspect a grease leak or a water issue, contacting your hood manufacturer is always recommended. Start by confirming whether your system is still under warranty.

If your unit is not covered, a professional technician can assess the welds, duct seams, grease vent integrity, and hood grease cup assembly to determine the safest repair approach.

Even minor grease leaks should not be ignored. Grease buildup increases fire risk and can damage surrounding equipment or surfaces over time.

Regular maintenance and professional inspections are the best way to catch small issues before they become costly repairs.

Partner With HoodMart for Reliable Ventilation Solutions

Grease leaks don’t just create messes; they signal deeper ventilation issues that can impact safety, efficiency, and code compliance. The right hood system, duct configuration, and accessories all play a role in preventing grease buildup and stopping leaks before they start.

If you're experiencing grease leaks, noticing buildup in your ductwork, or planning a new installation to prevent future problems, our ventilation experts are ready to help. Call us at 1.855.235.3632, start a live chat, or request a kitchen hood quote today to find the right solution for a cleaner, safer commercial kitchen.

Frequently Asked Questions About Grease Leaks

What causes a grease leak in an exhaust hood?

A grease leak can result from weak weld seams, buildup in the grease vent system, a full hood grease cup, or leaks around duct access doors.

How can I tell if it’s grease or water leaking?

Grease is thicker, darker, and slower-moving than water. Water leaks often occur after duct cleaning, while grease leaks develop from buildup or weld failures.

Can a full hood grease cup cause leaks?

Yes. If the hood grease cup is not emptied regularly, it can overflow and create the appearance of a grease vent leak.

Is cold air coming through stove vent openings related to leaks?

Cold air coming through stove vent areas may indicate airflow or duct sealing issues. While not always directly tied to grease leaks, it signals that your ventilation system should be inspected.

Are grease leaks dangerous?

Yes. Grease leaks can increase fire risk and cause damage if left unaddressed. Prompt professional evaluation is recommended.