A HEPA filter captures at least 99.97% of airborne particles at 0.3 microns, the hardest size to trap. That includes mould spores, fine construction dust, smoke particles, pollen and bacteria. Thorair stocks genuine replacement HEPA, pre-filters and activated carbon filters for every air scrubber and air purifier we sell.
Replacement filters by machine
| Machine | Pre-filter | Main filter | Optional |
|---|---|---|---|
| Pro HEPA Filter Air Scrubber (500 CFM) | HEPA pre-filter, 10 pack | HEPA 500CFM primary filter | HEPA activated carbon filter, premium carbon filter |
| Hulk Air Scrubber (1000 CFM) | G4 pre-filter 400 × 400 × 20 mm | Hulk primary filter | Carbon HEPA filter |
| Pro HEPA Turtle Carpet Blower | HEPA filter attachment | ||
| Thorair air purifiers | Washable pre-filter | Air purifier HEPA filter | |
How multi-stage filtration works
Stage 1, the pre-filter. A G4-rated fibre mat catches hair, lint and coarse dust. It is cheap and quick to change, and it is there to protect the expensive HEPA filter behind it. Stage 2, the HEPA filter. Pleated glass-fibre media traps fine particles through interception, impaction and diffusion. An H13 HEPA filter removes 99.97% of 0.3 micron particles; particles both larger and smaller are captured even more effectively. Stage 3, activated carbon. Carbon does not trap particles, it adsorbs gases and odours: smoke, sewage, paint and solvent fumes, and the musty volatile organic compounds given off by active mould.
When to replace a HEPA filter
- Airflow from the machine has dropped noticeably even with a clean pre-filter.
- The filter has been exposed to water or heavy smoke contamination.
- The media is torn, crushed or the seal is damaged.
- After a sewage (Category 3) or heavy mould job, regardless of appearance.
Pre-filters should be inspected every job and replaced when visibly loaded. Do not attempt to wash a HEPA filter: water damages the media and breaks the seal between pleats, and the filter will no longer meet its rating.
HEPA filters for dust and allergies at home
Household dust is a mix of skin, fabric fibre, pet dander, dust mite allergen and outdoor particles. Vacuuming and wiping deal with what has settled, but fine particles (PM2.5 and smaller) stay suspended and can only be removed by filtration. A HEPA air purifier running in the bedroom or living area reduces the load of allergens and fine dust, which is why they are recommended for asthma and hay fever sufferers.
Frequently asked questions
Can you wash a HEPA filter?
No. Washing damages the glass-fibre media and the filter will not perform to its rating afterwards. Only the pre-filter on Thorair machines is washable or replaceable at low cost.
How long does a HEPA filter last?
In an air purifier running continuously, 12 to 18 months. In a restoration air scrubber it depends entirely on the jobs: a heavy demolition or mould job can load a filter in days, a light water loss may barely touch it. Judge by airflow and contamination, not by the calendar.
What is the difference between H13 and H14?
H13 removes at least 99.95% and H14 at least 99.995% of particles at the most penetrating size. H13 is the standard for restoration and healthcare-grade air cleaning and is what Thorair scrubbers use.
Do I need the carbon filter?
Only if odours or gases are part of the problem: fire and smoke, sewage, chemical or paint fumes, or an active mould smell. For dust and spores alone the HEPA filter is enough.
