How we made this guide: picks, prices and specs come from our catalog and the makers' published specs, owner quotes come from customer reviews on our product pages and every guide is checked and edited by Trevor Hall.
You generally do not clean a true HEPA filter in an air scrubber or a HEPA vacuum, because the media is not made to be washed or brushed or blown out and the makers treat it as a replaceable part. Change the low-cost pre-filters often to protect it, and replace the HEPA itself when the machine's gauge or alarm shows it is loaded, or when it is wet or damaged.
It is a simple hand-tool job: on a Novair the pad and ring filter pull out by hand and the HEPA is held by four thumbscrews, and on a HEPACART you remove two screws and release four clasps.
Quick answer
Pre-filters: change when they look loaded, between jobs and often enough that the gauge stays low. HEPA: change when the pressure gauge reads in the maker's replace range, when airflow drops or when the filter is wet or torn. Washing: only where the maker's own manual says that exact filter is washable. Browse the HEPA air scrubbers and air scrubbers we carry.
Why a HEPA filter is replaced, not washed
HEPA media is a mat of fine fibers folded into deep pleats. Water weakens paper media, and a brush or compressed air can tear it or bend the pleats; a pinhole, or a frame that swells or warps and breaks the gasket seal, lets air bypass the media while the filter still looks fine. HEPACART's operation manual puts it plainly: its HEPA filter is made from a paper media that must be protected if there is a chance it will be exposed to moisture. For what the rating means and why the seal matters, read what a HEPA filter is.
A HEPA rating is a particle figure. Novatek lists its wood frame filters at 99.97% at 0.3 microns and its metal frame filters at 99.99% at 0.3 microns. A filter is not rated for gases or odors.
The filter stages and when to change each
Most air scrubbers and negative air machines stack filters so the low-cost stages take the dust and the expensive one lasts. The Novatek Novair 1000 and 2000 use three: a pad pre-filter, a two-ply ring filter and the final HEPA (or a 5 micron general purpose filter). HEPACART's cart uses a MERV 8 pre-filter in front of its HEPA. Vacuums add a paper bag.
| Stage | What it does | Change it when | Source |
|---|---|---|---|
| Pad pre-filter | Catches the bulk of the dust and debris | Gauge climbs, airflow falls or the pad looks loaded. HEPACART: whenever it shows dust and debris, and between jobs with dangerous contaminants | Novair 2000 manual, HEPACART manual |
| Ring filter or panel | Two-ply stage that catches what gets past the pad | Inspect when the gauge stays high after a new pad | Novair 2000 manual |
| HEPA | Final stage, rated at the maker's figure | Gauge reads 3.0 to 3.4 inches of water column on a Novair, airflow drops or the filter is damaged or wet. HEPACART: re-certify yearly at a minimum | Novair 2000 manual, HEPACART manual |
| Vacuum pre-filter | Takes load off the vacuum's HEPA stage | Every fifth paper bag, or when damaged or dirty outside | Novatek HEPA vacuum manual |
| Aeroclean 1900 Magnum stages | First stage pad, second stage ring panel, then the HEPA | Pad: daily on a 24-hour working cycle, or when it looks dirty. Ring: inspect at every pad change, change weekly or more often. HEPA: about every 350 hours of use, which the job can shorten or when the gauge reaches 3.0 inches of water column with clean first and second stage filters | Aerospace America owner's manual |
| Carbon (where fitted) | Adsorbs odors and gases, which the HEPA rating does not cover | On its maker's schedule; it is a separate part from the HEPA | Maker's manual |
The Novair manual also says the work atmosphere decides how often filters change, and that filters should be checked daily. For the vacuum side, see the commercial vacuum maintenance checklist.
Tools and parts for the job
You need the right filters for your model, heavy plastic bags to seal the used filters in, a HEPA vacuum for dust in the housing, gloves and the protective equipment the job calls for.
The machine
Novatek Novair 2000 Air Scrubber and Negative Air Machine
$1,430
Two-speed 2 hp air scrubber with a pressure gauge, plus alarm and light on this variant so a loaded filter is hard to miss.
Pad pre-filters
Novatek Novair Pad Pre-Filters
$45.50
Single-ply 5 micron pads in 20 or 40 packs for the Novair 2000 (24 x 24 in) and the 16 x 16 in Novair 700 and 1000.
Replacement HEPA
Novatek Novair 2000 Replacement HEPA Filter
$245
24 x 24 in HEPA for the Novair 2000 in wood frame, metal frame, DOP certified metal, metal mini-pleat and V-pack versions.
Step 1: Read the gauge first
Many scrubbers have a differential pressure gauge. Novatek's manual says it measures negative pressure on the clean side of the filters. As the filters load with dust, the reading rises. On a Novair, new filters start the needle low. Novatek says to check the filters once it reaches the 3.0 to 3.4 inch mark, because one or all of them are loaded by then.
| Gauge reading on a Novair | What it tells you |
|---|---|
| 1.0 to 2.5 inches | Normal start range with new filters |
| 2.8 to 3.2 inches | Alarm or light variants trigger in this range |
| 3.0 to 3.4 inches | Check the filters: one or all are loaded |
The gauge cannot tell you which stage is loaded, so Novatek's order is pad first: change it, run the unit on high, then check the gauge again before you touch the ring filter or the HEPA.
Step 2: Unplug and wear protective gear
Unplug the power cord before any service. Novatek's manual says to wear personal protective equipment during filter replacement and to follow federal, state and local regulations on the handling and disposal of hazardous materials. Aerospace America's manual urges approved protective equipment and respirators. If the last job involved a hazard such as lead or asbestos, the job's rules decide how the used media is bagged and disposed of. Our guides on HEPA vacuums for asbestos, lead and mold and dust control in construction cover those rules at a high level.
Step 3: Change the pad pre-filter
On a Novair, remove the black filter door, reach in and pull out the pad, then slide in a new one and replace the door. Plug in and check the gauge. Pads are the low-cost stage: the 20-pack for the Novair 2000 is $45.50, which works out to roughly two dollars a pad by our calculation.
Step 4: Check the ring filter
If the gauge is still above 3.0 inches after a new pad, follow the same steps to reach the two-ply ring filter, remove it, fit a new one and put the pad back in front of it. Filters for the Aerospace America Aeroclean 1900 Magnum come as three separate parts (pads, ring panels and the HEPA). Aerospace's manual says to inspect the ring filter at every pad change and replace it weekly or more often.
Filter set by stage
Aerospace America Aeroclean 1900 Magnum Replacement Filters
$105
Pads, ring panels and the 24 x 18 x 12 in HEPA for the Aeroclean 1900 Magnum, each sold as its own variant.
Step 5: Replace the HEPA filter
If the gauge is still in the replace range after the pad and ring are fresh, or the filter is torn, wet or has been through a contaminated job, the HEPA is the next change. On a Novair, per Novatek's manual:
- Remove the pad and ring filter as above.
- Loosen the four bracket thumbscrews by turning them counterclockwise.
- Push the filter brackets inward toward each other and remove them from the front.
- Grasp the right and left sides of the filter and pull it directly toward you. Dispose of the used filter as the job requires.
- Inspect the new filter's gaskets for cracks, gaps or defects. A defective gasket must be replaced.
- Insert the new filter gasket side first and press it firmly against the housing's internal rib, then refit the brackets and tighten the thumbscrews clockwise.
- Reinstall the ring filter, the pad and the filter door.
Replacement parts for the Novair 2000 start with the wood frame HEPA at $245. The metal frame versions are rated 99.99% at 0.3 microns and include a DOP certified option.
Changing the HEPA on a HEPACART
HEPACART's cart puts the HEPA after the fan, behind a MERV 8 pre-filter, so the pre-filter takes the heavy dust. Its manual says to inspect the pre-filter at regular intervals (weekly, monthly or quarterly, depending on use) and that more frequent pre-filter changes extend the life of the HEPA. It calls for the HEPA to be re-certified at least yearly and replaced if it shows damage or reduced airflow. It also says to always change the HEPA between jobs where potentially dangerous contaminants were present.
The steps in the HEPACART manual: unplug the cord, remove the two screws from the pre-filter cover and lift it off, release the four clasps on the fan housing, remove the fan housing, take out the dirty HEPA and fit the clean one noting the direction of airflow with gaskets upstream and downstream. Then reattach the housing, refit the cover and screws, test for operation and have the unit re-certified.
HEPACART filter
HEPACART 6" Replacement HEPA Filter for HEPACART Carts
$675
24 x 24 x 6 in, rated 99.99% at 0.3 microns, double gasketed. The MERV 8 pre-filter is a separate part.
Can you wash a HEPA filter?
A paper media HEPA, like the HEPACART one, is to be kept away from moisture. Some makers list a washable filter on a specific model, and when they do, the manual for that part tells you how. If the manual does not say washable, assume it is not.
For pre-filters, the same rule applies. Disposable pads are replaced, not rinsed. The white intermediate pre-filter in Novatek's HEPA vacuums is a fine non-woven filter. Novatek's HEPA vacuum manual says to change it with every fifth paper bag, or when it is damaged or shows debris on the outside, and not to attempt to clean it in any way.
Vacuum pre-filter
Novatek HEPA Vac Pre-Filter, 2-Pack
$59
White intermediate pre-filter for Novatek's 3.3 gal HEPA backpack and 15 gal HEPA floor vacuums.
If you run a HEPA vacuum, see what a HEPA vacuum is and browse the HEPA vacuums we carry.
Filter cost per job
The expensive stage should be the last one you change. The right column is our calculation from today's prices, in round bands.
| Part | Price | Our calculation |
|---|---|---|
| Novair pad, 20-pack | $45.50 | Pack price divided by pads: about two dollars a pad |
| Aeroclean 1900 Magnum pads, case of 50 | $105 | Pack price divided by pads: about two dollars a pad |
| Aeroclean 1900 Magnum ring panels, case of 24 | $168 | Case price divided by 24: about seven dollars a panel |
| Novair wood frame HEPA | $245 | HEPA price divided by that machine's pad price: about 100 pads |
| Aeroclean 1900 Magnum HEPA | $226.80 | HEPA price divided by that machine's pad price: about 100 pads |
| HEPACART 6 in HEPA | $675 | Sits behind a separate MERV 8 pre-filter, so there is no pad comparison |
Our calculation for one 5-day job on a 24-hour cycle with an Aeroclean 1900 Magnum, on Aerospace America's schedule: 5 pads at about two dollars each, 1 ring panel at about seven dollars and 120 of the HEPA's suggested 350 hours (about a third of a HEPA) comes to about $100 of filters at today's prices.
See what an air scrubber is and the negative air machines we carry. For the room side of the job, see what a negative pressure room is.
Common mistakes
- Washing, vacuuming or blowing out a HEPA to save money. The seal and the media can fail without any sign.
- Running the machine without the pre-filters.
- Changing the HEPA by the date alone. Novatek ties replacement to the gauge, Aerospace America gives 350 hours of use as a guide and HEPACART re-certifies its HEPA yearly.
- Skipping the gasket check.
- Installing the filter backwards. Both makers note direction: the Novair filter goes in gasket side first and the HEPACART filter needs gaskets upstream and downstream.
- Carrying a filter from a contaminated job to a clean one. HEPACART's manual says to change both the pre-filter and the HEPA between jobs where dangerous contaminants were present, and Aerospace America's manual says filters contaminated with asbestos, mold or lead must be disposed of properly.
Frequently asked questions
Can you wash a HEPA filter?
Generally no. HEPACART lists its HEPA as paper media to protect from moisture. A few vacuum makers list a washable HEPA on certain models, and for those only the maker's manual decides. When in doubt, replace it.
How often should you change a HEPA filter?
When the machine says so. On a Novair, that is when the gauge reaches 3.0 to 3.4 inches of water column or airflow is greatly reduced. On a HEPACART, replace it if it shows damage or reduced airflow, re-certify it at least yearly and change it between jobs with dangerous contaminants. Aerospace America suggests about every 350 hours of use, sooner on dirty jobs and recommends replacement once the gauge reaches 3.0 inches with clean first and second stage filters.
What happens if you run an air scrubber with a dirty filter?
Airflow falls, the pressure gauge rises and alarms trip on machines that have one. The Novair alarm and light option fires at 2.8 to 3.2 inches of water column. A loaded filter moves less air, and a loaded pad is the least costly way to fix that.
What do HEPA filters not remove?
The rating covers particles at 0.3 microns. It does not cover gases or odors, and a HEPA machine is not a mold remedy and kills nothing. Carbon media is used for odor, and mold is removed by remediation.
Do pre-filters last as long as the HEPA?
No. They are meant to be changed far more often. HEPACART's manual says more frequent pre-filter changes extend the life of the HEPA, Aerospace America says its ring filter protects the more expensive HEPA, and Novatek's HEPA vacuum manual says the intermediate pre-filter extends the HEPA's life.
What can I soak a vacuum filter in to clean it?
Only soak a filter its maker calls washable, and only in what that manual says. Novatek's HEPA vacuum manual says not to attempt to clean its pre-filter in any way, and a paper-media HEPA should stay dry. For cloth and cartridge filters on commercial vacuums, see how to clean a vacuum filter.
Keep the HEPA machine at its rating
Related guides
- What Is a HEPA Filter? Ratings, H13 vs H14, ULPA and Why the Seal Matters
- How to Clean a Vacuum Filter: Cartridge, Cloth, Bag and HEPA Filters on Commercial Vacuums
- What Is a HEPA Vacuum? True HEPA, Sealed Systems and When You Need One
- What Is an Air Scrubber? How a HEPA Air Scrubber Works and When You Need One
