How to Install Restaurant Kitchen Exhaust Ducts

How do you install restaurant kitchen exhaust ducts? Clear exhaust decides whether a kitchen can work safely. CHINENG shares installation basics.

Installation methods

1. Do not bury demountable duct joints in walls or floor slabs.

2. Embed hangers accurately and securely; keep embedded parts unpainted and clean. Unless designed otherwise:

1) Horizontal: spacing 4 m if diameter/long side <400 mm; 3 m if ≥400 mm.

2) Vertical: spacing 4 m with ≥2 fixings per riser.

3) Insulated ducts follow design.

4) No hangers at outlets, valves, or access doors; do not hang on flanges; add sway braces.

5) Fire dampers and motorized dampers need dedicated supports.

6) Flange gaskets 3–5 mm thick, not protruding inside; nuts on one side.

7) Horizontal levelness ≤3/1000 (total ≤20 mm); vertical plumb ≤2/1000 (total ≤20 mm).

8) Place damper operators for access; blades insert with airflow; install fusible links after system install.

9) Diffusers square, accurate, free-moving, firmly connected.

10) Flexible connectors neither too tight nor twisted.

3–6. Fabrication allowances cover fittings and hangers (not floor stands); flexible ducts may be metal or polymer films; guide vanes share one item; taper-duct uniform-supply systems use average size with labor ×2.5.

Exhaust design tips

1. Keep horizontal runs short—usually ≤15 m with ~2% slope and a cleanout at the end.

2. Duct velocity preferably ≥10 m/s so grease does not settle.

3. Branch dampers at hood connections; main duct about 8–10 m/s; hood throat about 4–5 m/s.

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