Choosing Filters for a Commercial Kitchen Make-Up Air Unit

Commercial kitchen make-up air units work in a tough environment. On one side, they draw in outdoor air that may carry dust, pollen and urban grime; on the other, they may sit close to heat, vapour and fine grease mist from kitchen operations. Choosing the right intake-side filter helps the unit deliver cleaner replacement air while staying serviceable in real-world conditions.

For facility managers, the main challenge is matching the filter to the site, the airflow and the maintenance plan. A filter that looks suitable on paper can still struggle if it blocks too quickly, is hard to fit correctly, or is not suited to the dust and grease loading around the building.

Start with the job the make-up air unit has to do

A make-up air unit does not usually need the same level of filtration as a cleanroom system, but it still needs protection from airborne debris. The intake-side filter is there to capture larger particles before they enter the equipment, reduce build-up on internal components and help keep the air path stable.

Before selecting a filter, clarify these site factors:

• •Whether the unit draws air from a rooftop, side wall or street-facing location
• •How close the intake is to exhaust outlets, loading docks, car parks or busy roads
• •Whether the surrounding area has high dust, soot, salt exposure or wind-blown debris
• •Whether the unit is exposed to heat, moisture, grease mist or general weathering
• •What airflow the unit needs to maintain during normal operation

If the intake is in a harsher location, a filter that is too fine can load up quickly and create unnecessary pressure drop. If the filter is too coarse, more debris may pass into the unit and shorten service intervals for other components.

Choose a filter grade that suits the intake conditions

For many commercial kitchen make-up air units, a staged approach works well. The first filter stage is often a coarse pre-filter designed to catch larger particles and protect downstream equipment. Depending on the site, a finer second stage may be appropriate where the intake air is dirtier or where the equipment designer has specified additional filtration.

In Australia, you may still hear filter classes described using older EN 779 terms such as G3, G4 or F5 to F9. These are still widely used in practice, although ISO 16890 is now the current European rating system. These standards do not convert directly, so it is better to select based on the actual application and the manufacturer’s airflow and dust-holding data rather than trying to match ratings by name alone.

For make-up air equipment exposed to heavier outdoor dust, a coarse or medium-grade intake filter is often a sensible starting point. Where the site is more exposed, or where the owner wants tighter control over dust entry, a finer filter may be justified if the fan can handle the added resistance.

When higher-efficiency filtration makes sense

Higher-efficiency filters can be useful where the intake air is particularly dirty or where downstream components need extra protection. However, finer filtration is not automatically better for every kitchen make-up air unit.

Consider:

• •Fan capacity and available static pressure
• •Filter face area and housing size
• •Dust loading at the site
• •Whether there is room for a deeper, lower-resistance filter
• •Access for safe replacement and inspection

If the system was designed for a lower-resistance filter, moving to a much finer product without checking the equipment can create operational problems. Where in doubt, confirm the design intent with the mechanical services engineer or building owner, especially if the system relates to AS 1668.2:2024 ventilation requirements.

Look for filter constructions suited to heat, grease mist and weather exposure

Heat and grease mist can affect some filter materials and housings over time. The best choice depends on where the filter is installed and what it is expected to face.

Useful features to look for include:

• •A rigid frame that holds its shape under airflow and handling
• •Filter media suitable for warm, humid or greasy air streams
• •Good sealing so air does not bypass around the edges
• •Enough depth or surface area to manage pressure drop more gradually
• •A design that can be removed without disturbing the whole unit

If the intake is outdoors, the filter and housing also need to cope with rain, wind-blown debris and temperature swings. On exposed sites, a weather louvre or intake hood may be needed ahead of the filter to keep out larger debris and direct rain. The filter itself should then act as the final intake barrier rather than the first line of defence.

Some filters are designed to be washable - check the product instructions. That can be useful in certain applications, but washability should never be assumed from appearance alone. If a washable product is specified, follow the manufacturer’s cleaning method and drying guidance carefully.

Make sure the filter fits the housing properly

A well-chosen filter will still underperform if it does not fit the frame correctly. Around commercial kitchen equipment, installation quality matters because vibration, heat and frequent maintenance can all affect how well the filter stays seated.

Check the following before ordering or replacing:

• •Exact nominal and actual dimensions
• •Frame depth and track style
• •Gasket or sealing requirements
• •Direction of airflow through the filter
• •Clearance for removal and inspection

If you are not sure how to measure the opening, our guide on how to measure an air filter can help. For non-standard housings, custom air filters may be the better option than forcing a close-enough size into a frame that was not designed for it.

Poor fit can lead to bypass, rattling, panel distortion or difficulty closing the access door. It can also make routine maintenance slower, which is a common reason filters get overlooked until the unit is already under strain.

Plan maintenance around the actual site conditions

There is no universal replacement schedule that suits every kitchen make-up air unit. Inspection frequency depends on the system, the site conditions and the dust load. A rooftop intake above a busy road will not behave the same as a protected intake in a cleaner part of the building.

A practical maintenance approach is to:

• •Inspect filters more often during dusty or smoky periods
• •Check the condition of the media, frame and seals during each visit
• •Monitor pressure drop where gauges are fitted
• •Replace or clean filters in line with manufacturer instructions
• •Record what you find so future ordering is based on site history, not guesswork

If the filter is loading faster than expected, that can point to changes in the surrounding environment, a damaged intake hood, or a filter choice that is not well matched to the duty. If you are already managing other air systems, our filter servicing and commercial filter servicing pages may be useful references for planning upkeep.

Choose a supplier that understands commercial kitchen conditions

A commercial kitchen make-up air unit is not just another ventilation point. It sits at the intersection of airflow, contamination control and practical maintenance access. The right filter needs to fit the unit, handle the site conditions and be realistic for the maintenance team to service.

Total Air Filtration is a family-owned air filter manufacturer and supplier based in Hillcrest, Brisbane QLD. We work with facilities that need practical intake-side filter solutions for commercial and industrial applications, including kitchen make-up air systems.

If you need help selecting the right intake filter, a replacement size, or a made-to-order option, we can supply or make the right filters for the job. Call 07 3800 3448 or request a quote. You can also contact us or browse our products and the industries we supply.