Process & access
Cleaning a greasy duct to bare metal takes more than a cloth. It is a kit of agitation, extraction, chemistry and inspection tools, each doing a job a vacuum alone cannot.
The short answer
Grease baked onto the inside of a duct will not simply wipe or vacuum away, so a proper clean uses a coordinated kit rather than a single tool. Broadly it breaks into four jobs: agitation to break the grease off the metal, extraction to capture what comes loose, chemistry to soften stubborn deposits, and inspection to see inside and prove the result. Each type of equipment does something the others cannot, and it is the combination - matched to your system during the survey - that gets a greasy duct back to bare metal.
Breaking the grease loose and capturing it
The workhorse for the runs is the rotary brush machine - a brush driven on a flexible cable, hydraulically or by drill, that scrubs the duct walls and can reach far along horizontal runs and up vertical risers. Multidirectional two- and three-brush heads let it reach into the corners of square and rectangular ductwork, not just round duct. For bends and tight junctions, pneumatic air whips use compressed air to flail the deposits loose where a brush cannot easily go.
Agitation is only half the job - the loosened grease has to be captured, not just moved around. That is the role of negative-pressure extraction and HEPA-filtered vacuums: the system is put under negative pressure so dislodged debris is drawn toward the collection point rather than spreading into the kitchen, and the HEPA filtration captures fine particles instead of blowing them back out. Working under negative air is what keeps the clean contained and the kitchen usable.
Softening deposits and seeing the result
Heavy, carbonised grease often needs chemistry and muscle before the machines can finish. Approved degreasers are applied to soften and dissolve the deposits, given time to dwell, and heavy build-up is hand-scraped and brushed off the surfaces. This manual work on the worst areas - around filters, at the base of risers, in the fan housing - is where a lot of the real grease is removed, and it is skilled, physical work rather than something a machine does on its own.
Finally, you cannot clean, or prove you have cleaned, what you cannot see. CCTV cameras and borescopes are pushed into the concealed runs to inspect the duct before cleaning, to check progress, and to confirm the result afterwards. Together with a Deposit Thickness Test or Wet Film Thickness Test, the camera provides the before-and-after evidence that shows the surfaces are below fifty microns. The inspection kit is what turns a clean into something verifiable, not just something claimed.
The kit exists to reach and prove, not just to scrub
The point of all this equipment is to reach the whole system and to prove the result - to clean the concealed runs a cloth never touches and to verify them below fifty microns. A contractor with the right kit can clean and document the full route; one with a bucket and a brush can only do the canopy. The equipment is what makes a genuinely compliant clean possible.
Questions
A kit of agitation, extraction, chemistry and inspection tools: rotary brush machines, air whips, negative-pressure and HEPA vacuums, degreasing chemicals, hand scrapers, and CCTV cameras or borescopes for inspection and verification.
It drives a brush on a flexible cable to scrub the duct walls, reaching along long horizontal runs and up vertical risers. Multidirectional heads let it clean the corners of square and rectangular ductwork, not just round duct.
It puts the system under negative pressure so dislodged grease is drawn to the collection point rather than spreading into the kitchen, and HEPA filtration captures the fine particles instead of exhausting them back out.
Yes, approved degreasers soften and dissolve heavy or carbonised deposits so they can be scraped and brushed off. The worst build-up around filters, risers and the fan is often removed by hand.
With camera inspection and a Deposit Thickness Test or Wet Film Thickness Test, which together provide the before-and-after evidence that the surfaces are below fifty microns.
Phoenix Duct Clean · by the numbers
We use rotary brush machines, negative-air extraction, degreasers and camera inspection to clean the full run - then verify it below fifty microns.