What is this called? It's not really flex duct

[mm]

I was in an appliance parts store and they had several pieces of heating duct in the corner, including a piece that I will need two of. This place doesn't sell the stuff. It was just stored there.

It is like a very short rectangular HVAC interior duct, that clamps to metal ducts at each end, and has 4 inches of heavy vinyl in between.

Like 15x20x4 inches.

Is there a name for what I saw?

It's meant to go between the furnace/AC and the rest of the house metals ducts, partly so furnace vibration won't get transmitted to the house. Although it seems not every installer uses them.

The label on it said flex duct but when I looked that up on the web all I found were long truly flexible ducts with built-in insulation that contractors now use sometimes to go from the main duct to individual rooms.

Thanks.

[Jon Danniken]

Try flex duct connector or flexible duct connector or duct connector.

Jon

[hrhofmann]

It is used to isolate noise from one part of the system into another part of the system. It is frequently found on the input and output sides of the main duct fairly close to the furnace/air conditioning unit to isolate motor/fan noise.

[mm]

Yeah, thanks. Mine don't have holes yet, but I think that will be soon.

[mm]

Hey, that's it. Thanks. Specifically duct connector. I haven't tried the other names yet.

Strangely, adding "rectangular" and going to the Shopping page mostly ended up with round connectors surrounded by a rectangular piece of sheet metal.

And so far I have found images but no residential quality for sale, I guess because they're bulky to ship and can be fabricated locally? But even if I don't find any in a catalog, at least I'll know what to ask for when I call places here. That's great.

Smitty, I did ask the only guy I saw, behind the counter, but he said, "I don't know. They're not mine."

[DT]

Find a distributor that carries Standex duct fittings. The "Snappy" (trade name), catalog is pretty much the standard around here. Here is the catalog page with the duct connectors. Any good heating/plumbing house should have them, or can order the size you need.

[mm]

Oh, wow, yes. That's the picture and I'm pretty sure the dimensions are in that list. Thanks a lot.

For the record, the dimensions are that of the duct it is mating with, measured NOT at the very end, right? That is, without any cleats on there now or anything else that might make the end bigger than the middle?

Hey, they even have an "Upcoming event" in Baltimore, although it was last September! ;)

[DT]

Right, that is the nominal duct size.

[mm]

Thanks.