Random vent that goes outside

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wickflair

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I am having such a hard time figuring this out. I have an exhaust vent outside my house that I can't figure out what it connects to. It's the same style vent used for my drier which is on the other side of the house. When tracing it runs through the basement ceiling via a 4in hose that is insulated. The only thing I can find in near location on the main floor where this ends is a white (what I thought was) a return vent for the furnace. Would there be any reason for a vent in a bedroom to exhaust outside?

Attached are some pictures to hopefully illustrated what I am talking about.
 

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Jeff Handy

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It could be a vent for a bathroom fan.
Or kitchen exhaust fan, or range hood or downdraft range exhaust.

Stick a leaf blower in there or a loud speaker, and try to find the noise or air flow in the house.
Although there will probably be a damper blocking most of the noise or air.
 

wickflair

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It could be a vent for a bathroom fan.
Or kitchen exhaust fan, or range hood or downdraft range exhaust.

Stick a leaf blower in there or a loud speaker, and try to find the noise or air flow in the house.
Although there will probably be a damper blocking most of the noise or air.
It's not bathroom vents. I went in the attic and they are vented outside.
 

wickflair

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After I took the mental off in the basement to see where it goes, this is what I found. It does connect right to the bedroom "intake vent" and then passes to the intake of the furnace and then whatever excess air is discharged outside.

And that is just a total guess.
 
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kok328

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This is the vent that is providing fresh outdoor air into your return air duct so that your not breathing stale recycled air.
 

wickflair

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This is the vent that is providing fresh outdoor air into your return air duct so that your not breathing stale recycled air.
That is I originally thought, but the outside vent is for air to go out and not in.
 

wickflair

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That looks like a return duct and the outside vent should just have a screen.
View attachment 23782
I removed the end and it was to the white vent in my back room. If I shine a light all the way down the end you can see where it connects outside to the vent as pictured. Same style as my drier.
 

dsteinhorn

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The fresh make-up air vent to the outside is usually ducted to the return air plenum of the furnace with a damper to control how much is pulled in. It doesn't see right to have a one way vent cover outside (that will block air coming in, not air going out) and then dump cold, unconditioned air right into a bedroom. I would re-route it to the return air plenum, put a suitable outside louvered grate over it with screen and put a damper inline to prevent excess unconditioned air from coming in.
 

wickflair

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The fresh make-up air vent to the outside is usually ducted to the return air plenum of the furnace with a damper to control how much is pulled in. It doesn't see right to have a one way vent cover outside (that will block air coming in, not air going out) and then dump cold, unconditioned air right into a bedroom. I would re-route it to the return air plenum, put a suitable outside louvered grate over it with screen and put a damper inline to prevent excess unconditioned air from coming in.
Thank you for the info. I'm not familiar with HVAC terms but the outside vent which is clearly wrong.. (not sure how long it's been like that.) is on the far opposite end of the bedroom return vent. Between them is a big Inlet to the furnace intake (probably not the right term but where it pulls air which passes the furnace filter and them enters the furnace). There is a manual slide damper after the intake but before the outside vent that is marked "full, 1/2, 1/4, closed). Would this be used to control what is pulled from outside? I moved in 7 years ago and it's always been like that. What have I been missing out on?
 

68bucks

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Some places require by code a fresh air intake. If you have a range hood or something like that you could pull exhaust from your furnace or hot water heater into your house. I had to install a fresh air vent when I installed a high volume range hood. It has a pressure switch that will open the damper when the fan is turned up high enough. I'd guess something like that.
 

68bucks

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Oh I might add that the inlet air I mentioned is dusted to the cold air return. That mixes it with indoor air to temper it so you don't notice it.
 

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