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Mysterious duct.

gyrfalcon Member Posts: 26
Any ideas what this duct is for? Besides being a major problem?  It’s hot and muggy around here. This is probably not helping!! 


  • Jamie Hall
    Jamie Hall Member Posts: 19,155
    Not a clue. Any access to it from above? Is air entering or leaving it? You may have to try blowing smoke or scent (peppermint works) into it with a fan to see where it heads!
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • mattmia2
    mattmia2 Member Posts: 5,749
    Is that a kitchen? looks like an old kitchen exhaust fan or just random exhaust fan, possibly that had the motor removed a long time ago.
  • pedmec
    pedmec Member Posts: 220
    judging by the infrared camera i'm thinking maybe a vent for the attic, if there is an attic above.
  • gyrfalcon
    gyrfalcon Member Posts: 26
    Cathedral ceiling / clerestory in kitchen.  Makes a dead zone for air movement. No ac regester or return in kitchen.  With AC on and really hot days, the wall sweats. Looks like the pipe goes to the wall area. I can’t see much beyond that. Can I just cover it up or fill with insulation ?  There is another strange duct like this one in my living room area.  Someone (several previous owners ago) had some wacky ideas they tried to implement, poorly.   
  • Zman
    Zman Member Posts: 7,357
    I have seen similar registers that are barometric relief dampers for evaporative coolers.
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • gyrfalcon
    gyrfalcon Member Posts: 26
    I see no outlet, wiring, controls or any other related items.   Any reason I cannot insulate and seal it off? 
  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 3,342
    edited June 15
    gyrfalcon said:

    I see no outlet, wiring, controls or any other related items.   Any reason I cannot insulate and seal it off? 

    It's your home. I can't see why not.

    Is this a manufactured home? Those homes can be low on combustion air availability and therefore have these installed to compensate. Other than that, I can't see any danger in sealing up those holes.

    Do you have any fossil fuel appliances in your home? Gas range, oil or gas furnace, Gas fired water heater, Gas fireplace, or wood stove are some examples. If yes, then I would make the vent cover a temporary insulation for now and test the home for Carbon Monoxide in the heating season.
    Edward Young
    Retired HVAC Contractor from So. Jersey.
    Services first oil burner at age 16
    P/T trainer for EH-CC.org
    Larry Weingarten
  • hot_rod
    hot_rod Member Posts: 16,566
    have a blower door test done on the home. Then cover the vent to see what a difference it makes. It must go somewhere.

    Can you get a ladder and see if it sucks or blows :)

    If you cover it, it might be nice to know where the other end of the duct is.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • gyrfalcon
    gyrfalcon Member Posts: 26
    I have gas appliances and a wood burner.  Boiler room has outside air pipe into the room.  I will look a little more and see what I find. 
  • Steamhead
    Steamhead Member Posts: 15,431
    Could be anything. We were working in a church once and there was a questionable duct they thought they could remove- turned out it was the output of the pipe-organ blower!
    All Steamed Up, Inc.
    Towson, MD, USA
    Steam, Vapor & Hot-Water Heating Specialists
    Oil & Gas Burner Service
    mattmia2CLambkcoppErin Holohan Haskell