8 min read · Filter Types
A kitchen grease filter is a metal filter installed in a range hood or commercial exhaust hood that separates grease droplets and vapour from cooking exhaust before the air enters the duct. Unlike a furnace filter, its job is not clean breathing air – it is fire safety and keeping grease out of ductwork, fans and the building envelope.
Residential range hoods typically use layered aluminum mesh filters, while commercial hoods over fryers, griddles and charbroilers use stainless steel or galvanized baffle filters designed to drain grease and resist flame. Both types are washable and reusable, but they are not interchangeable, and the rules for commercial kitchens are considerably stricter.
Quick facts
| Typical efficiency | Not rated by MERV; judged on grease extraction and flame resistance |
| Common types | Aluminum mesh (residential), stainless or galvanized baffle (commercial), plus specialty cartridge and mesh-baffle hybrids |
| Common sizes | Residential hood-specific sizes; commercial nominal sizes such as 16×20, 20×20 and 20×25 in., typically 2 in. deep |
| Typical applications | Home range hoods, restaurant and institutional cooking hoods, food trucks, cafeterias |
| Cleaning interval | Residential monthly or so; commercial from daily to weekly depending on cooking volume |
| Reusable? | Yes – washed and reinstalled; replace when bent, corroded or damaged |
| Relative cost | Low for mesh; moderate for stainless baffle |
| Best paired with | A regular professional hood and duct cleaning program (commercial) |
In this article:
- How grease filters work
- Baffle vs mesh: construction and comparison
- Fire safety and code basics in Canada
- Residential range hoods
- Commercial kitchens and restaurants
- Sizing and replacing grease filters
- Grease filters versus other washable filters
- Pros and cons
- Frequently asked questions
How grease filters work
Cooking releases a mix of grease vapour, fine aerosol droplets, water vapour and smoke. As the plume rises into the hood it cools, and much of the vapour condenses into droplets. A grease filter removes those droplets mainly by inertial impaction: the filter forces the airstream to change direction sharply, and the relatively heavy droplets cannot follow the turn, so they strike the metal surface and collect.
- Baffle filters use a series of overlapping vertical channels. Air snakes through an S-shaped path; grease hits the baffle walls and runs down into a trough or collection cup.
- Mesh filters use several layers of expanded or knitted aluminum. Droplets impact the fine strands and cling inside the mesh.
Neither design captures smoke particles or odours effectively. Those are gases or sub-micron particles that pass straight through; recirculating hoods add an activated carbon filter for odour, and commercial kitchens rely on ducted exhaust to remove them outdoors.
Baffle vs mesh: construction and comparison
| Feature | Aluminum mesh | Stainless baffle |
|---|---|---|
| Where used | Residential range hoods, some light-duty hoods | Commercial and institutional cooking hoods |
| Grease handling | Holds grease inside the mesh layers | Drains grease to a trough or cup |
| Fire behaviour | Grease-soaked mesh can feed a fire | Designed to act as a flame barrier when listed |
| Airflow resistance | Rises noticeably as the mesh loads | Stays relatively steady between cleanings |
| Cleaning | Sink or dishwasher; soak in degreaser for heavy build-up | Dishwasher, soak tank or professional exchange service |
| Durability | Light; easily bent | Heavy gauge; long service life if not dropped |
| Typical cost | Low | Moderate to high |
Galvanized and aluminum baffle filters are lower-cost alternatives to stainless, but stainless steel resists corrosion from strong degreasers and frequent washing best. Some hoods use proprietary cartridge or extractor designs; always replace them with the model the hood manufacturer specifies.
Fire safety and code basics in Canada
Grease is fuel. A heavily loaded filter or a greasy duct can carry a stovetop flare-up into the exhaust system, where it is far harder to extinguish. That is why commercial cooking exhaust is tightly regulated.
- In Canada, commercial cooking exhaust systems are generally designed, installed and maintained under the fire and building codes in force in each province, which reference NFPA 96 (ventilation control and fire protection of commercial cooking operations) and ULC-S647 (exhaust hoods and related controls for commercial and institutional kitchens).
- Commercial hoods are expected to use listed grease filters of the type the hood was approved with – in practice, baffle-style filters. Mesh filters are generally not accepted as the grease-removal device in commercial hoods because they hold grease and can sustain a fire.
- Filters must be installed in the correct orientation and angle so grease drains to the trough, with no gaps or missing filters. Blank panels, not empty openings, fill unused positions.
- The duct, fan and hood interior need periodic inspection and professional cleaning. High-volume operations such as charbroiling or 24-hour kitchens need it far more often than low-volume kitchens.
Specific requirements vary by jurisdiction and equipment. Follow your local fire code, the hood manufacturer's instructions, your fire suppression contractor and your insurer – they take precedence over any general guidance here.
Residential range hoods
Most Canadian homes have either a ducted hood that vents outdoors or a recirculating (ductless) hood over the range or built into a microwave. Both use mesh or slim baffle grease filters at the intake; recirculating hoods add a charcoal filter behind them.
- Wash mesh filters about once a month with regular cooking, more often if you fry or stir-fry frequently.
- Dishwasher cleaning works for most aluminum filters, though it can darken the metal over time. A soak in hot water with degreasing dish soap followed by a soft brush is gentler.
- Let filters dry fully before reinstalling, and replace any filter that is torn, bent out of shape or no longer fits snugly.
- Charcoal filters in recirculating hoods cannot be washed; replace them on the hood maker's schedule, often every few months.
In winter, a strong range hood exhausts heated air, so tight modern homes and condos may need make-up air to keep the hood working well. If your hood seems weak, check for a clogged filter before blaming the fan.
Commercial kitchens and restaurants
Restaurant, cafeteria, long-term care and school kitchens run hoods for many hours a day, so filter care is part of daily operations rather than an occasional chore.
- Cleaning frequency: kitchens with fryers, woks or charbroilers often wash baffle filters daily or several times a week; lighter-duty kitchens may manage weekly. Visible grease dripping from the filter face means it is overdue.
- Spare sets: keeping a second set lets staff swap filters at closing and wash the dirty set without running the hood unprotected.
- Filter exchange services: many operators use a service that swaps clean filters on a schedule.
- Damage: dented baffles leak grease and lose their flame-barrier role; replace them.
Remember that the exhaust filter is only one part of the system. Fire suppression, hood and duct cleaning, and fan maintenance must all be kept current.
Sizing and replacing grease filters
Commercial baffle filters are sold by nominal size (height × width × depth). The actual size is usually slightly smaller, so measure the existing filter rather than the hood opening and match height, width and depth. Check the handle style and the drain-hole position, which must line up with the hood's grease trough.
Residential filters are usually model-specific. Look for the part number on the filter frame or in the hood manual; if none is available, measure carefully, including the position of tabs or latches. A filter that rattles or leaves a gap lets grease bypass into the fan.
We stock washable aluminum filters suitable for many residential hoods and light-duty uses. For commercial baffle filters or unusual sizes, contact our custom filter or bulk orders team with the hood make and filter dimensions.
Grease filters versus other washable filters
Grease filters share the "wash and reuse" idea with washable HVAC filters and electrostatic filters, but the jobs are different. HVAC filters are rated by MERV for dust and fine-particle capture; grease filters are designed for droplet separation and fire behaviour. Never use a furnace filter, fibreglass pad or paper media as a substitute in a cooking hood, and never use a grease filter in a furnace expecting it to clean the air.
Pros and cons
| Advantages | Limitations |
|---|---|
| ✓ Washable and reusable for years | ✗ Do not remove smoke or odours |
| ✓ Protects ducts and fans from grease build-up | ✗ Mesh filters load and restrict airflow quickly |
| ✓ Baffle designs act as a flame barrier when listed | ✗ Frequent cleaning is labour-intensive |
| ✓ Low running cost | ✗ Damaged filters lose effectiveness |
| ✓ Simple to remove and clean | ✗ Commercial filters must match the hood's listing |
| ✓ Mesh filters are inexpensive to replace | ✗ Neglect creates a serious fire risk |
Shop at Canadian Air Filters
Washable filters · Carbon pleated filters · Custom filters · Bulk orders
Made in Brampton, Ontario and shipped across Canada. Need a size you can't find? Request a custom filter or ask about bulk pricing.
Frequently asked questions
Can I use mesh filters in a commercial kitchen hood?
Generally no. Codes for commercial cooking expect listed grease filters matched to the hood, which in practice means baffle-type filters; mesh holds grease and can sustain a fire. Check with your hood supplier and local fire authority.
How often should I clean my range hood filter at home?
About once a month is a good starting point for average cooking, and more often if you fry or sear regularly. If the filter looks sticky or the hood sounds strained, it is due.
Can grease filters go in the dishwasher?
Most aluminum mesh and stainless baffle filters can be washed in a dishwasher. Aluminum may discolour over time; a hot soak with degreasing soap is gentler. Always dry fully before reinstalling.
Do grease filters remove cooking smoke and smells?
No. They separate grease droplets, but smoke particles and odour gases pass through. Ducted hoods exhaust them outdoors, and recirculating hoods use an activated carbon filter for odours.
When should a grease filter be replaced instead of cleaned?
Replace it when it is bent, torn, corroded or no longer fits tightly in the hood. Damaged filters let grease bypass into the duct and, in commercial hoods, may no longer act as a flame barrier.
What size grease filter do I need?
Measure the existing filter's height, width and depth and note the handle and drain-hole positions. Commercial filters are listed by nominal size, so the actual dimensions are slightly smaller. For uncommon sizes, contact our custom filter team.