August 13, 2026 · 6 min read
Horizontal runs are the problem area
Grease collects fastest in horizontal duct sections where velocity drops. Those are also the sections furthest from any opening.
Without panels at reasonable intervals, cleaning stops at the plenum and the fan, leaving the middle untouched.
What code expects
Access openings are required at changes in direction and at intervals along horizontal runs so the entire interior can be reached and cleaned.
Panels must be grease-tight and rated for the application, not improvised covers.
How to tell if yours are missing
Look at your service report. Any honest cleaning company documents areas it could not reach.
If a report shows the entire system cleaned but you cannot find a single access panel on a long duct run, ask questions.
- Panels at every direction change
- Openings along long horizontal sections
- Grease-tight listed panels, properly gasketed
- Panels that are reachable, not buried above ceilings
Adding them is straightforward
Retrofitting listed access panels is routine work and immediately improves what a cleaning can accomplish.
It is usually the highest-value upgrade to an older exhaust system.
