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

Discussion in 'HVAC' started by Scarfone, Oct 25, 2012.

  1. Oct 25, 2012 #1

    Scarfone

    Scarfone

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    Hello,

    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.
     
    Last edited: Oct 25, 2012
  2. Oct 25, 2012 #2

    nealtw

    nealtw

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    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?
     
  3. Oct 25, 2012 #3

    Scarfone

    Scarfone

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    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.
     
  4. Oct 25, 2012 #4

    Wuzzat?

    Wuzzat?

    Wuzzat?

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    If
    your climate is warm and you want cooling or
    your climate is cold and you want warming
    then
    likely yes, but your labor and parts should pay for themselves in fuel savings within 10 years.
     
  5. Oct 25, 2012 #5

    nealtw

    nealtw

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    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.
     
  6. Oct 25, 2012 #6

    Scarfone

    Scarfone

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    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.
     
    Last edited: Oct 25, 2012
  7. Oct 25, 2012 #7

    Wuzzat?

    Wuzzat?

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    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
    http://www.tradekey.com/products/flexible-rectangular-duct.html
    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!
     
    Last edited: Oct 25, 2012
  8. Oct 25, 2012 #8

    nealtw

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    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.
     
    Last edited: Oct 25, 2012
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  9. Oct 27, 2012 #9

    notmrjohn

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    ", 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.
     
  10. Oct 28, 2012 #10

    Wuzzat?

    Wuzzat?

    Wuzzat?

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    This wordplay only works with text. But it's pretty good.
     
  11. Oct 29, 2012 #11

    nealtw

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    If the duck are to noisy just tape their bills closed. (duck tape)
     
  12. Oct 31, 2012 #12

    Scarfone

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    Well, I guess from what I hearing the lack of foam board or insulation between the siding and house is a problem just as I suspected. However, I don't know if its just no insulation down the return air portion or the entire side of the home. The house is 2 story with brick on the bottom floor and alum. siding on the top floors. The bottom of the siding on the outside is not sealed down to the brink portion so I probably could be able to lift the siding in various places to see in there is foam board other places other then where the return air run. Perhaps the just didn't insulate the air return portion between the studs by the rest is of the side of the home is? This area of the home is neither the front or back of the home. it is on the side of the home below a window.

    The siding is alum. and nailed down. Would this be something I could do? Perhaps pull the siding off the entire side of that house and install foam board and then replace the same siding? I know this would not be a 1-2 hour job but I don't know if I can afford someone doing it. Does the foam board need to be nailed down? Or could I cut pieces I need and slip them upward by lifting the edge of bottom of the siding? I have also noticed the spare bedroom right next to mine is also a very cold room. Now I shut the heat to this room and haven't looked down the air return in this room to see if it has the same problem. BTW, I am using the metalic tape and not regular duct tape. What that runs out, was going to switch to mastic.



    Λ
    / \
    / \
    / \
    / \
    /siding \
    / [] \
    -------------
    | |
    | |
    | brick |
    | |
    -------------------------------------------------------------------
    [] = cold air return : No to scale/angles
     
    Last edited: Oct 31, 2012
  13. Oct 31, 2012 #13

    Scarfone

    Scarfone

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    Sorry,

    Some reason my attempt at making a quick diagram did turn out but I think you get the picture.
     
  14. Oct 31, 2012 #14

    nealtw

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    Aluminium has to be removed from the top down. So you have the whole side of the house stripped, but it can be done. I wouldn't try to pry it open at the bottom, you will spoil it. Have you tryed plugging the return and leaving the bedroom door open to see if heat in that room gets better or not?
     
  15. Oct 31, 2012 #15

    Scarfone

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    No, haven't tried plugging it yet. I was told I need a return in any room or it would make the problem worse, meaning less heat. I'm not sure why that would be the case. I know heat rises and it is in theory suppose to pull it down slightly to evenly heat the room. But I don't see how plugging it could make the problem in this case any worse.

    As far as pulling the siding. I have never done any type of work like that. Would I be able to pull all the nails and remove it carefully enough to be reinstalled? I'm giving me self a 70% chance of being able to pull the siding and reinstall it.

    I guess I would have to first determine if it's the entire side of the house without any foam board or just the return air runs. If it's just the runs, maybe I could slide a cut piece under the siding or possibly open the air return in the basement and slide one narrow long piece all the way up. But something tells me that foam board should and needs to be tacked down.
     
    Last edited: Oct 31, 2012
  16. Oct 31, 2012 #16

    nealtw

    nealtw

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    In order to get air into a room, you also have to have a way to get the air out. For a test leave the door open so air can get out.
     
  17. Nov 1, 2012 #17

    notmrjohn

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    Now that the duck has stopped quacking, we can hear ourselves think about the problem, or problems, as usual a simple one task project has multiplied into a few projectiles. Seems you have two problems, loose ducts, possible lack of insulation.
    Use screws to fasten ducts where you can reach it, if choice is only one of either tape or mastic, tape is easier to use, easier to bridge over unavoidable gap than try to fill with goop. Any foam-board you slide into space needs to be secured some way so it doesn't just slide back out, a screw, nail, tack, staple, even tape.Tape or caulk gaps where it butts against studs.

    I dunno if anyone answered your original question, the duct being in an uninsulated area is not making the room cold, cold air returning to furnace would make furnace work harder and would affect entire house. You pro'lly wouldn't even notice a temp difference, might notice furnace working. Loose return ducts would do the same, maybe more so as they might pull in really cold air.

    Are return ducts needed? Depends on house configuration. My house has no return ducts at all. One story, air handler in central hall way. Air returns thru open doors and under doors, thru grill in closet door. One room does have a problem with being too hot or too cold due to not enough return, but it is opposite of what you fear. Too cold from AC, too warm from heater. This is mostly due to outlet damper in there not staying adjusted, too much air coming in.

    A room not being warm or cool enough is usually due to lack of circulation in the room. Cool or warm air sits in pockets, warm at ceiling as you said. A return can help there, but so can a ceiling fan, reversed slow speed in winter pushes warm air across ceiling down the walls. A fan at table level, near a wall,pointed up can have same effect to lesser degree. Ultimate ducting would be two systems one opening at ceiling level, other at floor, with openings across room from each other,with reversable fan. In winter warm air enters at floor, leaves at ceiling, summer cool air enters at ceiling. So you can block off return duct, leave door ajar and see what happens.

    Cold room and cold duct are caused by apparent lack of insulation in walls.
    You can remove bottom strip of siding for inspection. You'll need special but readily available tool to uncrimp aluminum siding. It is not difficult but siding is flimsy, easily bent when unattached. Work slow and careful, with a helper to support long flimsy piece. You may have to remove more than one row to really see inside. You would also need the tool if you start at top. If you decide to remove siding, I can post links to procedure and a few tricks and problems I've run into.

    If there is a closet against exterior wall, and it is drywall, it is easy to cut an inspection hole there. patching hole does not have to be as perfect as if in room.

    From inside out you should find a vapor barrier, insulation, sheathing, siding. Batt insulation may have integral vapor barrier, may be another barrier under siding over sheathing. Walls may have been originally filled with a loose fill insulation, which settles over years, especially if there is inadequate blocking. It is not unusual to find 8' wall with upper 5' uninsulated. Very possible they filled from top and ddin't fill under window.

    Your drawing looked fine in E-mail notification. A few options for replacing, renewing or installing insulation. From inside or outside, some more involved than others, some more effective than others, depends on what you find, especially concerning sheathing and vapor barriers.

    I think I'm thru for now, release the duck. The quaking shouldn't make it any harder to understand my confusing rambling than if you'd smeared his bill with Malone's Marvelous Mallard and Muscovy Miracle Mystery Mastic.
     
  18. Nov 18, 2012 #18

    Scarfone

    Scarfone

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    Well, from getting myself in deep and looking down the air return the best I could I have found the following.

    The air return does not use the entire space between the studs and does not go down the wall to the basement. In fact, I followed a cable line that was ran through and it appears the cold air run goes down then curves into a very narrow area, almost under the edge of the flooring in the room. This area I am seeing, that is open and I can see the siding, could be easily sealed off using well cut pieces of wood and some caulk. Obviously this does not address the lack of foam board or anything under the siding in that area, but at at least it will seal the air run off from the this area, which BTW, is very cold air when I place my hand in their. No doubt it's pulling very cold, outside air from the small gaps and what I believe to be drain holes for water on the bottom edge of each piece of siding.

    Someone cut a serious corner here when they put the siding up but I am in in position right now to pull the siding down and deal with this the correct, thou more extensive and expensive way. I will in a sense build a rectangle box with the 2 long sidings missing and place this in the cavity and then seal it off from the outside elements. I am hoping this will increase the pull this air return has on the bedroom since right now it's pulling from everywhere under the siding and pretty much outside air. I will have to deal with the real problem in the spring.
     
  19. Nov 19, 2012 #19

    nealtw

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    Maybe you could cut a return air vent right into the floor and just close the wall up with insulation or foam or? until you get to fix the outside wall properly. The return air should not be anywhere near the outside like that.
     
  20. Nov 19, 2012 #20

    notmrjohn

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    Sounds like a plan to me. Anything to stop that direct entry of outside air. Those are drain or weep holes in the siding. Instead of blocking off the "channel" with wood, consider usinf foam insulation panels. You mite could cut a longer piece as wide as the space and slide it up in there against the siding. then cut a few pieces to stack on each other to block the end. Hold and seal the end in place with adhesive caulk.

    Back when fuel was cheap, folks didn't worry so much about insulation. I grew up in Texas Panhandle when and where natural gas was almost cheaper than water, There still should have been some kind of sheathing behind that siding. Often the only thing between siding and studs was a layer of tar paper.. In winter furnaces ran full bore 24/7.
     

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