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Scarfone 10-25-2012 09:13 AM

Cold Air Return open under my siding, no duct, normal?

After last years winter and working overtime to pay my heat bill, I have been looking for ways to improve my heating costs. I bought the home last October and am getting around to leak proofing my heating/cooling system.

The home is a 2 story structure. The lower half is solid brick, while the top portion is aluminum siding. My heating unit is a forced air style located in the basement. My master bedroom, which is furthest from the heating source, is the coldest room in the home. No problems on the main floor.

While painting my bedroom, I pulled the cold air intake grate off and something caught my eye. It had a metal hood coming up but I could see a line of "daylight" further past the CAR. With a flashlight, I then could see the back of my siding, where it all connects together. No type of foam board or insulation. The return runs between 2 studs and goes directly down the wall and into the basement. It goes into a cold air channel between the joists in the basement ceiling along the basement wall. It appears to be the cold air return for 2 bedrooms on the second level. It then has an elbow and duct work that goes to the main cold air trunk.

What I began doing is sealing the leaks in all the duct work in the basement which had no type of sealing at the duct joints. I found a fair amount of leakage for the heat duct that runs off the main trunk and goes to the cold bedroom. I have found numerous small leaks in the heat ducts and am working on those. Numerous leaks in the heating unit itself which I have patched already. I have noticed a difference in the amount and force of heat now coming out in the bedroom.

However, I am curious if this cold air return where I can see the siding is normal and or allowing cold air to come in my bedroom. I can't find a fresh air vent to the HVAC. I have heard from several different sources that this is normal and from others that it is not. Mind you the same leaks I have found on the heat side of the system I am also finding on the cold air side in the duct work in the basement which I am also working on sealing.

The unit has central air and the screen type filters that I have taken out and cleans. My question is simple, yet the description is long which I am sorry for. But is the cold air return in the master bedroom normal? Is this causing the cold room? The attic looks to have fresh blown in insulation, so new it looked like a fresh winter snow so I am thinking it's not the problem.

Thanks for reading this long and boring problem but I am really wanting to know what to do because I can't afford to pay someone to pull siding off and fix things if need be.

nealtw 10-25-2012 09:35 AM

I think you found the problem. Is the top floor an addition? It dosn't sound like something a pro would do. We call them cold air returns but the pros like to call the "return air" because it should still have some heat left in it when it returns to the furnace. I have never seen ducks or returns running up an out side wall. Is this connected to returns on the main floor, or are they a different duct?

Scarfone 10-25-2012 02:08 PM

Second story is not an addition. It is not connected to any other air returns, goes straight down the exterior wall through the studs. Would it be a good idea to pull the sheet metal from the joists in the basement where this return flows to, then sorta push up duct work the the way to the air return hood in the cold bedroom. Then slide some foam board between the new duct and siding? Hope that makes some sense.

Wuzzat? 10-25-2012 02:38 PM


Originally Posted by Scarfone (Post 78982)
Would it be a good idea to pull the sheet metal from the joists in the basement where this return flows to, then sorta push up duct work the the way to the air return hood in the cold bedroom.

your climate is warm and you want cooling or
your climate is cold and you want warming
likely yes, but your labor and parts should pay for themselves in fuel savings within 10 years.

nealtw 10-25-2012 02:56 PM

I am hoping one of the hvac pros will come along and help out. In the mean time it sounds like the house was built with out a return upstairs and this is someones attempt at solving a problem by making it worse. Have a look around and see if you can find another place where you could run a duct in the interior, like closet above closet or something.

Scarfone 10-25-2012 02:59 PM

Wow. 10 years! Yes, that is something there is pros and cons to. I live in Detroit area so I get both hot and cold seasons. The only other reason it would be worth it then would be the noise issue. Since the air return empties into an area of siding with no insulation, I hear everything going on in my neighbors driveway which can be maddening since I work midnight shift.

So there not being a duct really isn't causing the furnace to work harder since it's pulling in very cold air? Or would sealing up all the duct joints and air return gaps in the basement be a better cost savings measure? I will be going on a caulking spree outside later today for doors and windows. Sadly, there really is no other wall to put the air return on the way the house is constructed. The bedroom in question is about a front living room that connects with the dining room via arch way. The stairs to go up are open and not walled off.

Now, one other question I just thought of in regards to the air return in question. Would this cold air, when my unit is not running, allow for cold air to seep into my bedroom floor? I haven't gotten a good look at the edge of the floor that is near the air return but it could very well be open like a = sign. The top line being my bedroom floor and the middle being the gap between the bedroom and lower level room. God I'm starting to sound like a pain in the butt, sorry.

Wuzzat? 10-25-2012 03:04 PM

Half the people move after 7 years and almost all move by 14 years.

Go with the biggest smooth rigid duct you can. If not, try
but flex ducts have considerable resistance to airflow.
You can also use a duct booster fan.

CFM and FPM and noise and static pressure and the furnace blower curve and the resistance of registers and ducts are all interdependent so graphical solutions are used frequently: see the Engineering Toolbox and efunda sites.

Pneumatic circuits are more complicated than electrical circuits because air is compressible and warm air acts differently than cold air.
ASHRAE is the ultimate authority but their books are costly and they don't readily lend them to libraries. With one book I got, I was required to read it in the library. BOO, ASHRAE! Shame on you!

nealtw 10-25-2012 04:05 PM

Running a duct in that cavity dosn't do anything about the lack of insulation. It might be better to seal that off and just add vent to the bedroom wall so air can go to the hallway and down the stairs, maybe a boaster fan the heat duck to that room
And yes the furnace is working harder if you are super cooling the air and between furnace runs as that room cools it will suck fresh cold air into that room.

notmrjohn 10-27-2012 04:17 PM

", I then could see the back of my siding,...No type of foam board or insulation"
There is no insulation or vapor barrier in exterior walls? That needs to be addressed. SOON.
If there was insulation then at least all your air leaks would be inside the house. Even with insulation ducts should not be in exterior walls.

I hope you are using duct caulk and/or metal foil duct tape and not duck tape.

Despite neal's advice a "heat duck to that room " is nice and cozy, what with the down and all, but the constant quacking will keep you awake. "boaster fan" indeed, 50 likes in only 48 posts! I just made it 51, cause my spel Czech done went back to Prague in disgust, anne neel's advise generally maiks cents.

Wuzzat? 10-28-2012 03:06 PM


Originally Posted by notmrjohn (Post 79115)
my spel Czech done went back to Prague in disgust

This wordplay only works with text. But it's pretty good.

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