The building used to have an oil tank (as per an environmental assessment) and chimney. It currently has a natural gas powered boiler to heat the building.
Oops I deleted the post. I wrote: Ok thanks, this looks more like it! But these ducts are vertical whereas mine are horizontal. They look like binoculars haha
This was one of the fittings that was part of the level 1 curriculum sheet metal class that I went through and then taught for 5 years. I’ve seen a couple hundred of them made, but the first ever in use. Even finding one on a Google search was difficult.
I’m not sure why that one was installed horizontal. They are made to create a natural or up draft.