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Instructions

Airotrust® Magnetic Filter Frame Instructions, Filter Selection and Maintenance

The Airotrust® Magnetic Filter Frame is a reusable frame designed to hold compatible 24-inch by 24-inch filter media directly over a ceiling supply diffuser or appropriate return grille.

Airotrust is the frame, not the filter. Filter media is purchased separately and may be supplied by Airotrust or sourced from another manufacturer. This gives each facility the flexibility to choose MERV-rated particulate media, activated-carbon media, or other compatible filters based on its indoor air-quality needs.

This page provides general guidance based on Airotrust testing, third-party airflow testing, and experience with installations in offices, schools, healthcare settings, manufacturing facilities, warehouses, and other commercial buildings.

Every building and HVAC system is different. The building owner is responsible for selecting the filter media, determining how many frames to install, choosing installation locations, monitoring filter condition, and confirming compatibility with the HVAC system.

For permanent installations, large projects, older HVAC equipment, sensitive environments, or systems with existing airflow concerns, consult a qualified HVAC professional or test-and-balance contractor.

What Is Included in the Airotrust Frame Kit?

Each Airotrust® Magnetic Filter Frame Kit includes four identical molded slats.

Each slat contains:

  • Dovetail-style interlocking connectors

  • Integrated high-energy rare-earth magnets

  • A molded channel that helps retain the filter media

  • Structural features that create a rigid frame once assembled

The four slats connect to form one complete square frame.

Filter media is not included unless it is specifically listed as part of the product package being purchased.

Before Assembling the Frame

Choose a clean, firm, non-ferrous work surface.

A wood, plastic, laminate, or similar nonmagnetic table is preferred. Avoid assembling the frame directly on a steel workbench, metal cart, or other ferrous surface because the magnets may attach to the surface and make the assembly process more difficult.

Protect finished surfaces with a clean towel, cloth, piece of cardboard, or other nonabrasive material.

Before assembly:

  • Confirm that all four slats are present

  • Inspect the dovetail connectors for shipping damage

  • Remove any packaging materials

  • Make sure the magnets are securely contained within the slats

  • Keep loose metal objects away from the work area

  • Wear appropriate eye protection when using any tapping tool

  • Keep fingers clear of the connecting joints

The molded connections are designed to fit tightly so the finished frame remains rigid during installation and use.

How to Assemble the Airotrust Frame

Step 1: Position the First Two Slats

Place two slats on the work surface so the end of one slat aligns with the dovetail-style connector on the second slat.

Make sure the molded filter-retaining channels face toward the inside of the forming frame.

Step 2: Interlock the First Corner

Slide or press the dovetail connectors together.

Begin with steady hand pressure. Keep the pieces aligned so the connection enters straight rather than at an angle.

The joint is intentionally designed to fit firmly. Some pressure may be required before the pieces fully lock together.

Step 3: Add the Third Slat

Align the third slat with the open end of one of the connected pieces.

Press the dovetail connection together while keeping the slats flat against the work surface.

Step 4: Add the Fourth Slat

Connect the fourth slat to the third piece, then align the final open corner.

Press the final dovetail connection together until all four corners are fully seated.

If Light Tapping Is Needed

Some joints may require light tapping to fully seat the dovetail connections.

Do not strike the molded frame directly with a metal hammer or other hard tool.

Use the following method:

  1. Place a folded towel, washcloth, or other soft protective material over the area being tapped.

  2. Support the frame on a firm, non-ferrous surface.

  3. Keep your hands and fingers away from the joint and striking area.

  4. Use a rubber mallet, plastic-faced mallet, or similar non-marring tool.

  5. Tap lightly and evenly while confirming that the pieces remain properly aligned.

  6. Stop if the connector appears misaligned, twisted, or damaged.

Do not use your bare hand as a hammer. Steady pressure or light tapping with a protected, soft-faced tool provides better control and helps protect both the frame and the person assembling it.

Step 5: Inspect the Completed Frame

Once all four pieces are connected, inspect every corner.

Confirm that:

  • All four dovetail joints are fully seated

  • The frame is square

  • The slats are level with one another

  • There are no visible gaps at the corners

  • The filter-retaining channels face inward

  • The magnets are secure

  • The frame is not cracked, twisted, or damaged

The assembled frame should feel rigid.

The slats may be separated later if necessary, but repeated disassembly is generally not required for normal filter replacement.

Before Installing the Frame

Confirm the following before installing Airotrust:

  • The ceiling uses a suspended grid with nominal 2-foot by 2-foot ceiling tiles

  • The ceiling grid is ferrous and attracts a magnet

  • The supply diffuser or return grille is securely supported

  • The surrounding ceiling tiles and grid are undamaged

  • The selected filter media fits within the assembled frame

  • There is adequate clearance around the frame

  • The installation will not interfere with sprinklers, smoke detectors, lights, sensors, speakers, cameras, walls, bulkheads, or other ceiling-mounted equipment

  • The HVAC system is operating properly

  • Existing central filters are not excessively dirty or restricted

  • The selected filter media is appropriate for the intended application

Some suspended ceiling grids are made from aluminum or other nonmagnetic materials. Test the grid with a magnet before attempting installation.

Do not install Airotrust over:

  • Kitchen exhaust

  • Bathroom exhaust

  • Hazardous-process exhaust

  • Smoke-control equipment

  • Combustion-air openings

  • Grease exhaust

  • Fume exhaust

  • Any grille where added resistance may create an unsafe condition

  • Any opening connected to a life-safety function

How to Install the Filter Media

Step 1: Confirm the Filter Size

The Airotrust® Magnetic Filter Frame is designed to hold compatible nominal 24-inch by 24-inch filter media.

Confirm the actual filter dimensions before installation. Nominally sized filters can vary slightly by manufacturer.

Step 2: Check the Airflow Arrow

Most disposable filters include an arrow showing the intended direction of airflow.

The arrow should point in the direction the air is moving.

For a supply diffuser, the arrow will generally point away from the ceiling and toward the occupied room.

For a return grille, the arrow will generally point toward the ceiling and into the return-air system.

Follow the filter manufacturer’s instructions when available.

Step 3: Place the Filter Into the Frame

Lay the assembled frame on a clean surface.

Position the filter media inside the frame so it sits evenly within the molded retaining channels.

Confirm that:

  • The filter is centered

  • The media is not folded or damaged

  • The filter frame is not twisted

  • The airflow arrow is facing the proper direction

  • The filter does not interfere with the magnetic mounting surfaces

How to Attach Airotrust to the Ceiling Grid

Raise the assembled frame and filter toward the ceiling diffuser or return grille.

Align the frame with the ferrous ceiling grid surrounding the vent.

The integrated rare-earth magnets will attach directly to the metal grid. The action is similar to placing a strong refrigerator magnet against a metal surface.

Allow each side of the frame to make full contact with the grid.

After attachment:

  • Confirm all magnets are contacting the grid

  • Verify that the frame is level

  • Check that the frame is centered over the diffuser or grille

  • Confirm the filter is secure

  • Make sure the frame is not contacting a sprinkler, light, detector, sensor, wall, or other obstruction

  • Gently check that the frame is firmly attached before removing the ladder

Do not release the frame until you are certain the magnets have made secure contact with the ferrous ceiling grid.

Use appropriate ladder and workplace-safety procedures during installation, inspection, and filter replacement.

Where to Install Airotrust

Airotrust can be installed over certain ceiling supply diffusers or return grilles in suspended ceilings.

For most indoor air-quality applications, supply-side installation is the recommended starting point.

Supply Diffusers

A supply diffuser is the ceiling vent that delivers heated, cooled, or conditioned air into the occupied room.

Installing Airotrust over a supply diffuser places filtration near the final point before the air enters the space. This is referred to as final-stage filtration.

Final-stage filtration may help reduce:

  • Airborne dust

  • Pollen

  • Mold spores

  • Pet dander

  • Fine particulate

  • Wildfire-smoke particles

  • Smog-related particulate

  • Certain odors when activated-carbon media is used

  • Particles introduced or remaining downstream of the central HVAC filter

A central HVAC filter remains important. Airotrust adds another filtration point at the end of the air-distribution path.

After air passes through the primary HVAC filter, it may still travel through:

  • Supply ductwork

  • Internally lined ducts

  • Dampers

  • Variable-air-volume boxes

  • Flexible connections

  • Ceiling plenums

  • Diffusers

  • Areas where outside air is blended into the system

Placing filtration at the diffuser creates a final opportunity to reduce particulate before the air enters the occupied room.

Return Grilles

A return grille draws room air back toward the HVAC system.

Airotrust may be used over certain return grilles to help reduce the amount of dust entering the return-air path. However, return grilles may carry a higher volume of air than individual supply diffusers.

Return-side installations require additional consideration when:

  • One return grille serves several rooms

  • The return already contains filter media

  • The HVAC system has limited return-air capacity

  • The return handles a high volume of air

  • Two filters would be placed in series

  • The system has a history of frozen coils

  • Existing airflow is already weak

  • The HVAC equipment is older or poorly maintained

For many office, classroom, healthcare, and commercial applications, supply-diffuser installation provides a more practical final-stage filtration approach.

How Many Supply Diffusers Should Be Covered?

Air follows the path of least resistance.

If several supply diffusers serve the same room or HVAC zone and only some are filtered, more air may be delivered through the unfiltered diffusers.

For the most consistent results, use the same type, depth, and condition of filter media on comparable supply diffusers within the same room or zone.

This does not mean that every diffuser throughout an entire building must always be covered.

Facilities may choose to begin with priority areas such as:

  • Offices connected to manufacturing areas

  • Classrooms

  • Conference rooms

  • Reception areas

  • Medical or first-aid rooms

  • Cleaner-air break rooms

  • Areas occupied by people with allergies or respiratory sensitivity

  • Rooms affected by wildfire smoke

  • Rooms affected by outdoor pollution

  • Areas where visible dust has been a persistent problem

When using partial coverage, monitor:

  • Airflow

  • Room temperature

  • Noise

  • Employee comfort

  • Heating and cooling performance

  • Indoor particle levels

  • Differences between filtered and unfiltered rooms

Large installations should be reviewed by a qualified HVAC professional or test-and-balance contractor.

HVAC and Airflow Considerations

Every filter adds some resistance to airflow.

The amount of resistance depends on:

  • MERV rating

  • Filter construction

  • Filter depth

  • Pleated media area

  • Air velocity

  • Filter condition

  • Filter loading

  • Number of covered diffusers

  • Existing duct condition

  • Fan capacity

  • HVAC controls

  • Central filter condition

  • Coil cleanliness

  • Building pressure

  • Outdoor-air intake

A higher MERV rating does not automatically mean that a filter will create an unacceptable restriction.

Filter depth, media design, available surface area, and face velocity also matter.

Why Face Velocity Matters

Face velocity is the speed at which air passes through the exposed filter area.

At a central HVAC filter rack, a large amount of air may be forced through a relatively concentrated filter area.

At a ceiling diffuser, airflow is generally distributed across the diffuser face. The resulting face velocity through a full-size filter can be much lower.

Lower face velocity can:

  • Reduce pressure drop through the media

  • Increase the time particles interact with the filter fibers

  • Allow more effective use of the available filter area

  • Reduce the restriction associated with certain filter media

  • Improve practical filter performance in some applications

The same filter media can perform differently depending on where and how it is installed.

Third-Party Airflow Testing

Third-party airflow testing of selected Airotrust installations found that tested configurations maintained approximately 92% to 96% of baseline airflow while producing only small changes in measured system pressure.

Those results apply to the systems, filters, and conditions that were tested.

They should not be interpreted as a guarantee for every building, filter, or HVAC system.

System performance should always be evaluated based on the actual installation.

ECM and Variable-Speed Motors

Many modern HVAC systems use electronically commutated motors, commonly called ECM motors, or other variable-speed fan systems.

These motors may adjust their output within a designed operating range when system resistance changes.

This does not mean that an ECM motor can compensate for unlimited restriction.

Problems can still occur when:

  • Filters are excessively dirty

  • Multiple restrictive filters are installed

  • Return-air capacity is inadequate

  • Coils are dirty

  • Ductwork is blocked

  • The system is already operating near its airflow limit

  • Fan settings are incorrect

  • The HVAC system is poorly maintained

Older constant-speed systems may be less able to compensate for added resistance and should be evaluated more carefully.

Stop and Investigate if You Notice

Remove the filter media and contact an HVAC professional if the installation causes:

  • A major reduction in airflow

  • Whistling

  • Unusual air noise

  • Excessive filter movement

  • Filter bowing

  • Uneven room temperatures

  • Longer heating or cooling cycles

  • Frozen evaporator coils

  • Condensation around the diffuser

  • HVAC fault codes

  • Fan or motor problems

  • Excessive pressure at doors

  • New drafts

  • Pressure imbalances

  • Any condition that appears unsafe

Airotrust should not be used to compensate for an HVAC system that is dirty, damaged, improperly balanced, undersized, or operating incorrectly.

Choosing the Best Filter for Your Application

There is no single filter that is best for every building.

Filter selection should be based on:

  • The contaminant being addressed

  • Desired particle reduction

  • Airflow requirements

  • HVAC equipment condition

  • Room use

  • Filter depth clearance

  • Desired service life

  • Existing central filtration

  • Occupant sensitivity

  • Indoor and outdoor air-quality conditions

MERV 8

MERV 8 is a practical choice for general dust control and applications where maintaining low resistance is a priority.

Common applications include:

  • Lint

  • Larger dust particles

  • Pollen

  • Fibers

  • General visible particulate

  • Basic office or commercial dust control

MERV 8 may be a good starting point for older systems or facilities that are especially concerned about airflow.

High-Capacity MERV 9 or MERV 11

These filters provide a middle ground between basic dust control and higher-efficiency fine-particle filtration.

Common applications include:

  • Dust

  • Pollen

  • Mold spores

  • Dust-mite debris

  • Pet dander

  • General allergy-related particulate

High-capacity media can provide a useful balance between particle capture, airflow, and filter service life.

MERV 13

MERV 13 is commonly selected when reducing finer particulate is the priority.

Common applications include:

  • Fine dust

  • Wildfire-smoke particles

  • Smog-related particulate

  • Respiratory aerosols

  • Bacteria-carrying particles

  • Smaller allergy-related particulate

  • Pet dander

Airotrust particle-count testing has shown strong reductions with properly selected MERV 13 media. Certain tested configurations produced particle reductions approaching the high-90-percent range under specific test conditions.

Actual results will vary based on:

  • Filter manufacturer

  • Media construction

  • Particle size

  • Face velocity

  • Filter condition

  • Filter loading

  • System runtime

  • Room conditions

  • Outdoor-air introduction

  • Door traffic

  • Testing method

  • Building leakage

MERV 13 is generally more restrictive than lower-MERV media and should be evaluated for compatibility with the HVAC system.

Activated-Carbon Filters

Activated carbon is used primarily for certain gases, volatile compounds, and odors.

Common applications include:

  • Wildfire-smoke odor

  • Food odors

  • Animal odors

  • Tobacco-smoke odor

  • Waste-related odors

  • Certain chemical odors

  • Certain industrial odors

Carbon filtration and particulate filtration perform different jobs.

Activated carbon is not automatically a replacement for MERV-rated particulate media.

A carbon filter may reduce odor while allowing fine particles to pass. A particulate filter may reduce smoke particles while allowing some odor-causing gases to remain.

For wildfire smoke and similar events, carbon and particulate filtration may be used together as part of a layered strategy.

Keep unused carbon filters sealed until needed. Carbon begins adsorbing compounds whenever it is exposed to air, gradually using its available capacity.

HEPA Media

HEPA media may be appropriate for specialized applications, but it usually creates more resistance than standard MERV-rated filters.

Do not install HEPA media over a diffuser or return grille without evaluating:

  • Airflow

  • Static pressure

  • Fan capability

  • Filter area

  • System performance

  • Room air delivery

  • Heating and cooling performance

Filter Depth

Where ceiling clearance allows, a deeper pleated filter may provide more filter media surface area than a shallow filter.

More surface area can:

  • Reduce resistance through the media

  • Increase dust-holding capacity

  • Extend service life

  • Improve airflow compared with a shallow filter using similar media

Check clearance before using deeper filters.

Do not allow the filter or frame to interfere with:

  • Sprinklers

  • Lighting

  • Walls

  • Doors

  • Detectors

  • Sensors

  • Cameras

  • Speakers

  • Ceiling access

  • Other building components

Filter Inspection and Replacement

There is no universal replacement interval.

Filter life depends on:

  • Particle concentration

  • Manufacturing activity

  • Outdoor-air quality

  • Door traffic

  • Occupancy

  • Filter type

  • Filter depth

  • System runtime

  • Air velocity

  • Construction activity

  • Renovation

  • Wildfire smoke

  • Seasonal pollen

  • Indoor dust generation

  • Filter surface area

In a clean office, a filter may last for several months.

In a manufacturing environment, warehouse, construction area, or severe wildfire-smoke event, the same filter may load much more quickly.

Recommended Inspection Practice

Inspect newly installed filters frequently until a normal replacement pattern is established.

Check filters:

  • Within the first week after installation

  • At regular intervals thereafter

  • During and after wildfire-smoke events

  • During high-pollen seasons

  • After construction or renovation

  • When indoor particle readings rise

  • When airflow changes

  • When room comfort changes

  • Whenever visible dust develops

The visible location of the filter makes inspection straightforward. Look up and compare the installed filter with a clean replacement.

Replace the Filter When

Replace the media when:

  • It has become noticeably dark

  • It is visibly loaded with dust

  • Airflow has decreased

  • The filter is damaged

  • The media is bowed

  • The filter is torn

  • The media becomes wet

  • Odors begin returning through carbon media

  • The filter has been exposed to unusual contamination

  • The filter manufacturer’s recommended service limit has been reached

  • Particle monitoring indicates declining performance

Do not wash, vacuum, or blow compressed air through disposable media unless the filter manufacturer specifically approves that cleaning method.

Why Dirty Filters Must Be Replaced

As a filter collects particulate, its resistance generally increases.

An excessively loaded filter can:

  • Reduce airflow

  • Affect heating and cooling performance

  • Increase fan workload

  • Create uneven room temperatures

  • Increase filter deformation

  • Reduce useful service performance

  • Contribute to equipment problems in systems already operating near their airflow limits

A filter may continue capturing particles as it loads, but the increasing resistance can eventually outweigh the benefit of leaving it installed.

If replacement media is not immediately available and the existing filter is heavily loaded or creating a significant airflow reduction, remove the dirty media until an appropriate replacement can be installed.

Do not continue operating with a visibly clogged, damaged, wet, or deformed filter.

Seasonal and Temporary Use

Airotrust may be used continuously or deployed for specific events and seasons.

Temporary or seasonal applications may include:

  • Wildfire-smoke events

  • High-pollen periods

  • Flu and respiratory-illness seasons

  • Nearby construction

  • Building renovation

  • Dust-producing maintenance

  • Odor events

  • Temporary occupancy changes

When filter media is removed, the reusable Airotrust frame may remain installed or be removed, cleaned, and stored.

Cleaning the Airotrust Frame

Remove the disposable filter media before cleaning the frame.

Wipe the high-impact polystyrene frame with:

  • A soft cloth

  • Mild soap

  • Water

  • A cleaner confirmed to be compatible with plastic

Do not use:

  • Aggressive solvents

  • Abrasive pads

  • Open flame

  • Excessive heat

  • Harsh chemicals that may damage the plastic

  • High-pressure washing

Inspect the frame, magnets, slats, and dovetail connections before reinstalling.

Do not use a damaged frame.

Rare-Earth Magnet Safety

Airotrust contains strong rare-earth magnets.

  • Keep fingers clear of pinch points

  • Keep magnets away from magnetic storage media

  • Keep magnets away from sensitive electronics

  • Keep loose metal objects away during assembly and installation

  • People with implanted medical devices should follow the device manufacturer’s guidance regarding strong magnets

  • Keep frame components away from small children

  • Do not use the frame if a magnet becomes loose or damaged

Need Help Selecting a Filter?

Airotrust can provide general application guidance based on the building type, indoor air-quality concern, diffuser layout, filter goals, and prior testing experience.

Helpful information includes:

  • Number of rooms

  • Ceiling height

  • Number of supply diffusers

  • Number of return grilles

  • Existing central filter type

  • HVAC equipment age

  • Desired contaminant reduction

  • Current airflow concerns

  • Available filter depth

  • Whether the concern involves dust, smoke, allergens, odors, or industrial particulate

  • Whether the installation will be permanent or seasonal

Final responsibility for filter selection, system compatibility, installation location, maintenance, and code compliance remains with the building owner and the appropriate HVAC or facility professional.