Abandoned Ducts in the attic

The pictures attached show a heating supply duct (or possibly a cold air return duct) in the attic of a circa 1955 home (bungalo) in Toronto Ontario. It was located just inside the attic access hatch. Pictures a little blurry, sorry.

I ran the furnace to see if it was either supplying or returning air and neither case was true (disconnected and / or sealed over the years I guess). I recommended sealing the opening in case a critter found its way into the attic and crawled into the open duct where it there got stuck and met its maker…

Has anyone ever seen this before? I can’t see it being a supply duct for an attic air conditioner… we don’t have many of those up here - or at least none that I have seen.

The house has its own A/C external compressor unit (over 20 years old).

Any suggestions?

Attic Duct 2 Web.jpg

Attic Duct 1 Web.jpg

I have seen it before, Nothing drastic or even do anything unless it enters the home envelope. Then block and seal it off.

I see a lot of kitchen exhaust fans and or bathroom exhaust fans that will be terminated into the attic in this fashion.

I suppose the house is too old for combustion air from the attic??

Was the furnace in a closet?
I ask because that looks more like a makeup air duct to supply fresh air to the furnace.

looks like makeup air to me. in that case you wouldnt see much air movement upon operating the furnace

The furnace is in the basement. There is no duct termination in the basement that I can link to this duct in the attic, unless it connects with a cold air return somewhere in a wall - which is very possible.

Thanks to all for your responses.

Same here, I see that all the time. Both in round ducts and rectangular like in the picture.

That is simply trash left over from the install which should have been taken out years ago.