Attic air shared with a/c-heater system closet. WHY?

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Old 01-06-10, 01:32 AM
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Question Attic air shared with a/c-heater system closet. WHY?

I really need to know about this, because gas systems scare me and I don't want to have created a hazardous situation by sealing up something I shouldn't have.

My question is basically about attic space shared with the house & if it is necessary on a gas heating system which shares an a/c and was purchased new within the last 5 years. I have sealed off a space in which I could see the attic and we were getting a cold draft from it (this winter and heat in summer) and I am worried if I cut off a flow of air that was intended to be there for the unit to cool off or breath or if the contractors just never sealed it off as they should've.

My gf got a new a/c & heating unit for her home. It is inside a closet that sits over the intake vent, a typical setup. I imagine under the back side of the unit there is a horizontal hole cut out to take in the air for recirculation (intake), otherwise the closet has a solid plywood floor.

Inside the "unit" closet there are 2 air ducts.

Air Duct 1: Is 10" by 10" square and is open space such that I can see the under boards of the roof in the attic from the closet unit area, by looking up with a flashlight from the living room. Inside and passing through this duct is about a 4" pipe which flows heated air into the house's duct system. Between this 4" heat-air pipe and 10" duct, which the 4" heat-air pipe passes through, is just open air space. Tonight since it is 25F outside I could feel a very brisk cold draft coming through this duct before I sealed it off. Also, there is no insulation on this 4" heat-air pipe and I say that because I don't know if there should be as in a/c duct's I've seen insulation wrapped around the duct work in other attics.

Air Duct 2: Off to the right of the unit & air duct 1, is another duct that is rectangular in shape and comes down from above to about 3/4 the distance of the height of the closet. I also feel a cold draft coming out of this duct and do not understand its purpose.

Why would attic air be allowed inside the unit's closet?

Lastly, I think we might have this same problem too:
http://forum.doityourself.com/gas-oi...-continue.html
, but I am not sure as it only occurs when we set the heating to 67 degrees F and tonight and the past few nights its been under 32 outside - around 25 F.
 
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Old 01-06-10, 08:02 AM
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Gas equipment located in a "confined space" needs to have specific provisions made to insure the availability of sufficient combustion air to burn the gas and operate the appliance correctly.

Usually that involves two air openings into unconfined spaces, one high and one low, the size dependent on the BTU input to the equipment.

So those openings are probably there for a purpose.
 
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Old 01-06-10, 07:48 PM
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Pictures?

I can't quite understand what you are saying about the ducts. Can we have some pictures? Pix can be posted on photobucket.com (free) or similar site & a link to them posted here.
 
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Old 01-07-10, 11:28 AM
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SeattlePioneer said it right - simpler - it is a confined space and gas heating.... and the duct openings for it are 1 HIGH on side and 1 LOW side... I guess this is for continual draft for the burn.

To me it seems excessive to have all this air in there, but I guess its needed and I will pull the sheet of aluminum off the duct I sealed off.

I suppose the best thing to ensure we're not sharing attic air is to seal the a/c-heating closet door off at its edges with some gasket material, as it is in the living room.

Thanks Seattle. You might've saved us from a broken heater or house fire......who knows.
 
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Old 01-08-10, 12:00 AM
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Question

How much duct air space should the unit have on the high duct side?

How much duct air space should the unit have on the low duct side?

IE: in inches - how big should the ducts be

Now, I'm trying to figure out if too much cold air is getting to the furnace/heater.
 
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