A kitchen exhaust fan pulls out heat, smoke, and greasy vapour. Over time, that vapour turns into sticky build-up on filters, the fan blades, and inside the housing. When you stay on top of it, the kitchen feels fresher, the airflow improves, and the fire risk drops.
This guide is written for busy food kitchens: offices, restaurants, cafes, takeaways, clubs, pubs, and catering spaces.
Why a clean kitchen exhaust fan matters
Kitchen exhaust fan build-up grease and oil particles rise with the heat and get trapped in the system. If left alone, they form a sticky layer that blocks airflow. The fan has to work harder, which wears it out faster and can make noise or let smoke linger. More seriously, thick grease acts as fuel for fire. Fire and Rescue NSW notes that a build-up of grease and fat in ovens, rangehoods, and grills can ignite easily one of the common kitchen fire triggers.
Australian Standard AS 1851 sets out clear maintenance rules for these systems to keep fire risks low. Many insurance policies and food safety checks also expect regular cleaning and records. A clean system means better ventilation, fewer odours, less chance of mould or bacteria growing in damp areas, and longer life for the whole setup. It also makes daily cleaning easier and keeps the Kitchen hygienic and looking fresh.
When the kitchen exhaust fan needs cleaning clear signs
Don’t wait for things to happen. Check for these signs:
- There is grease or sticky residue on the filters or inside the hood.
- Strong odours from cooking that stay around for a long time.
- The fan sounds different than it usually does.
- Grease running down the sides or onto the cooktop.
- Less suction means that steam or smoke stays about instead than being drawn away fast.
There is a yellowish or brownish buildup on the blades or duct openings (if you can see them).
Safety First: Clean Your Kitchen Exhaust Every Time
Before you touch anything:
- Switch the fan off and isolate power (at the switch or breaker). If your site uses lock-out and tag-out, follow it.
- Let the equipment cool so you are not working near hot surfaces.
- Wear PPE: gloves, eye protection, and non-slip shoes.
- Control slip risk: Grease and water on floors are a hazard.
- Cover food and prep areas so that cleaning splashes cannot contaminate anything.
- Never mix chemicals. Mixing products can create dangerous fumes.
Kitchen Exhaust Fan Cleaning Kit: What You Need
- Heavy-duty dishwashing liquid and/or a labelled kitchen degreaser
- Hot water (very hot helps soften grease)
- Non-scratch pads, soft brush, and microfibre cloths
- Plastic scraper (for thick build-up)
- A bucket or a large tub for soaking filters
- Bin bags, paper towels, and a sealable container for grease waste
- Step ladder (rated, stable, with a spotter if needed)
Know the Kitchen Exhaust Parts So You Clean the Right Thing
Most systems have:
- Filters (baffle or mesh)
- Hood/canopy (the stainless steel area above cooking)
- Fan assembly (motor housing and blades/impeller)
- Grease catch points (cups, trays, drains)
- Ductwork (the hidden pathway to the roof or discharge point)
- Roof fan (on many sites)
A lot of smell and airflow issues come from the fan blades and housing, not just the filters.
How often to clean the kitchen exhaust fan schedule you can actually follow
Frequency should match how hard the kitchen works.
Use this as a practical baseline:
- Daily (end of shift): wipe visible splatter and the hood lip
- Weekly: wash filters (or swap with a clean spare set if you have one)
- Monthly: deep clean the hood underside and the fan area you can safely access
- Every 3 to 6 months: inspect for hidden build-up (especially if frying or char-grilling is heavy)
- Every 6 to 12 months: specialist clean for ductwork and roof fan, depending on build-up and cooking volume
If your site cooks with heavy grease output for long hours, shorten the cycle. Research from UNSW Sydney indicates that high-efficiency exhaust hoods over gas cooktops can capture more than 75% of air pollutants, directing them outside to improve indoor air quality in Australian homes and kitchens. However, lower flow rates or non-external venting reduce effectiveness, underscoring the kitchen’s need for proper system maintenance and cleaning in Sydney and nationwide.
Step-by-step: Clean the kitchen exhaust fan properly
Step 1: Set up the area
Plan this for a quiet period or after-hours if you can. Clear food away, then cover benches and nearby appliances with plastic sheeting. Place absorbent pads or old towels under the work zone to catch drips.
Step 2: Take out the filters and soak them
Remove the filters carefully and place them in very hot water with dishwashing liquid or a suitable degreaser. After soaking, scrub with a soft brush, rinse well, and let them air-dry completely.
Tip: If a filter still feels sticky after washing, grease is still there. Soak and scrub again. Never refit damp filters.
Step 3: Wipe the hood underside and rim
Put the degreaser onto a cloth first rather than spraying it into the air. Wipe the underside thoroughly, then use a non-scratch pad for stubborn patches. Focus on joins, corners, and the front edge where build-up usually thickens.
Step 4: Empty and wash the grease catch parts
If your hood has a grease cup or tray, remove it and scrape the contents into a sealable container. Avoid sending thick grease down the sink. Wash the cup or tray with hot soapy water, rinse, dry fully, then refit.
Step 5: Clean the reachable fan area safely
This is the part most kitchens miss, and it matters. Isolate the power first. Don’t spray water anywhere near the motor, and only open panels that are designed for access. Use a plastic scraper to lift heavy build-up from the housing and blades, then wipe using degreaser on a cloth. Clean both sides of the impeller blades because even a thin film can reduce airflow and upset the balance.
If your unit uses belts or bearings, listen and look for early warning signs such as squealing, wobbling, or a worn belt. Fixing these early prevents bigger breakdowns.
Step 6: Refit parts and check airflow
Put the dry filters back in, make sure panels are secured, then restore power and run the fan for a few minutes.
Quick check: hold a paper towel near the hood edge at a safe distance from the heat. You should feel a steady pull. If the draw is still weak, the restriction is often further along in the ducting or at the roof fan.
Step 7: Clean up and control waste
Bag greasy towels and dispose of them properly. Keep wash water and collected grease contained so it doesn’t spread through the kitchen or end up where it shouldn’t.
When to Stop DIY and Call a Professional for the Kitchen Exhaust Cleaning
You can usually clean the filters and the easy-to-reach surfaces yourself as part of your regular routine. But if you do not have the right tools, the grease layer is heavy, you cannot reach the ducting, the fan is mounted high, or you need formal proof for insurance, audits, or site rules, it is best to bring in a specialist for a full deep clean.
Call a specialist when:
- You suspect duct build-up (smell returns quickly, airflow stays weak)
- Grease is visible past the filter line
- The roof fan is coated, and it is not safe to access
- You cannot open the access panels to inspect the duct
- You need compliance-style reporting, before-and-after photos, or certificates
A professional cleaning team like Westlink Commercial Cleaners has the access equipment, safety controls, and experience to clean the full airflow route without harming the motor, wiring, or fan balance. They can reach hidden sections, remove heavy build-up safely, and confirm the system is pulling air properly. Many jobs also include before-and-after photos and a written service record, so you have clear evidence that the exhaust path has been cleaned end to end.
Post-clean checks: how to tell the kitchen exhaust fan is truly clean
Once everything is dry, switch the fan on (high setting if you have it) and do these quick checks. This is what “done properly” looks like:
- Touch test (edges and filter tracks): Run a clean finger or paper towel along the hood lip, corners, and the filter rails. It should feel dry and smooth, not tacky or slippery. The towel should come away clean, not yellow or brown.
- Look inside what you can safely see: Shine a torch into the housing and check the fan blades. You want no dark film, splatter spots, or oily shine on the surfaces you can view without opening sealed parts.
- Run test (fan on): Let it operate for 1 to 2 minutes. You should see no droplets, no drips, and no streaks forming or running down. If liquid starts to appear, that usually means residue is still loosening or water is trapped in corners.
- Smell and airflow check: The kitchen should feel fresher with less lingering cooking smell. Air should pull strongly into the hood. A simple check is holding a tissue near the intake, it should lift and draw in, not hang flat.
If any check fails, focus on the problem area again (rails, corners, blade faces, inner rim), then re-test with the fan running.
Simple log for kitchen exhaust fan cleaning template (copy this)
- Date and time
- Areas cleaned: filters, hood underside, fan housing, blades, grease cups
- Cleaner used (name and dilution)
- Issues found: leaks, worn belt, noisy bearing, loose panel
- Who did the work
- Next due date
Conclusion
Kitchen exhaust fan cleaning is one of the simplest ways to improve airflow, reduce odours, and cut fire risk in any busy food kitchen. Stick to a realistic routine: wipe the hood daily, wash filters weekly, and deep clean the reachable fan area each month, then book a specialist to inspect and clean ducting and roof fans on a set schedule. Always isolate power, use PPE, and handle grease waste safely. If airflow stays weak, smells return fast, or grease is visible beyond the filters, stop DIY and bring or book a professional to clean the full exhaust path and provide proper records.
Frequently Asked Questions
How often should we clean the exhaust fan?
Filters usually need weekly cleaning in busy kitchens, and the fan area needs a monthly deep clean. Full system intervals depend on cooking volume and hours.
Is cleaning the filters enough?
No. Filters help, but grease still travels and can coat the fan blades and housing. That build-up reduces airflow and increases risk.
What is the fastest way to degrease baffle filters?
Soak first in very hot water with dishwashing liquid or a suitable degreaser, then scrub and rinse.
Can we pressure wash the fan blades?
Avoid blasting water into the motor or electrics. Use controlled wiping and scraping. If the fan is heavily coated or roof-mounted, get a specialist.
Why does the kitchen still smell after we cleaned the filters?
Odour often comes from build-up on fan blades, inside the housing, or further into the duct. If smell returns quickly, inspect deeper.
What causes grease to drip from the hood?
Common causes are overloaded filters, clogged grease cups/drains, or heavy build-up on internal surfaces that liquefies when warm.
How do we know if the duct needs cleaning?
Weak airflow, persistent odour, visible grease beyond filters, or repeated smoke issues are strong signs.
The fan is squealing. Is that a cleaning issue?
Sometimes, but squealing can also be belt wear or bearing issues.
What records should we keep?
Keep a cleaning log, before/after photos when possible, and any service paperwork or certificates from specialist work.
What should we do before a specialist visit?
Book off-hours, brief staff, cover equipment, clear access, and plan a post-clean inspection walkthrough.
