What are the parts of an air ventilation system called?

Specifically, I'm looking for two things:

  1. The "tubing" that the air goes through (and you can climb into)
  2. The part that connects to the room, where air flows out (and you can take off to climb into the system)

It doesn't have to be technical, it's for a short story that I'm writing. Children climb into "1" through "2".

What I had in mind was "shaft" for the first one, and "grate" for the second one.

What are better words for these?

  • 1
    My first thought was air duct and air vent. I'm not sure that they refer to these parts though. Oct 15, 2016 at 14:55
  • 2
    I think I'd use ducting and grille respectively. You have indicated the size, but... Where are these words to be used? Do you need a technical term for an engineering drawing? A word for a novel? Different contexts may need different words.
    – Andrew Leach
    Oct 15, 2016 at 14:56
  • Nothing technical. It's for a short story that I'm writing. Children climb into "1" through "2".
    – Ati
    Oct 15, 2016 at 14:58
  • @Ati Please edit your question to include everything which could possibly assist. Do check the tag info for single word requests: there's a checklist.
    – Andrew Leach
    Oct 15, 2016 at 15:10
  • They climb through the shaft to the grille/grate.But rather than climb, how /they about inched their way up/down through the shaft on their knees/? Yes, ventilation shaft. Or course, you can say they climb through the ducting, but that sounds awful.
    – Lambie
    Oct 15, 2016 at 17:05

2 Answers 2


It's a grille or a grate if it returns air (return chamber), and a register or diffuser if it supplies air (plenum chamber). Failing that, grilles and grates typically do not have moving parts, whereas registers and diffusers usually do.

Avoid using air shaft, as those are typically vertical and run the entire height of a building.

The kids might have to turn back once they reach the main air shaft, having traveled through the ductwork (aka, ducts) all the way to it, after having removed the [grate/grille/register/diffuser] to gain access (or they'll likely risk certain death by falling several stories).

If this is a simple passive fresh-air intake from an air shaft, they'd have had to remove a register/diffuser (assuming it articulates) to get inside, only to be blocked (hopefully) by a grille/grate at the inlet, where the duct meets the shaft.

They may or may not encounter a damper somewhere inside the ductwork, which they'd have to squeeze by. Dampers are usually just a flat piece of sheet metal, hinged at the middle so that they can control the flow of air by restricting it.

Technically speaking, the piece of duct that you attach these covers to is known as a boot. Boots connect to branches, and branches connect to trunks. Trunks connect to chambers, and chambers connect to the air handler. Air handlers are integral to every forced air furnace.


Basically the hvac air distribution system starts at the heating/cooling unit. The air goes into a plenum from which it goes into ducts to distribute it to individual rooms. Where the duct transitions to the room the is a grille known as a diffuser.

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