Air return vents lead to dead end


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Old 01-12-08, 03:21 PM
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Air return vents lead to dead end

Hello. After 2 years of being in my custom built home, I have never been able to determine why 3 bedrooms upstairs were always either too warm in the summer or too cold in the winter. Well...I feel stupied here, but I have just realized that the return vents in each of these 3 rooms lead to nothing. For some reason, I would vaccum over all my return vents downstairs due to a layer of visable dust, but never saw any noticable dust on 3 vents upstairs - I just assumed since they are not occupied, that no dust is stirred up and never really paid attention to it. Well, I just took the vents off and found they lead to nothing. The white vent just covers a hole in the wall which is lined with studs, but does not connect to the return system like the rest do...hence, no air movement unlike the others in my return vents in my home. The other returns in my home are pulling so much air that a few of them "humm" and keep the rooms very comfortable. Anyway, to all the experienced HVAC folks...if my HVAC installers put these return vents in each room, shouldn't they (even by HVAC Laws) be connected to my main return system? I wanted to get educated on this subject before I contact my HVAC installer and/or lawyer. I wouldn't think they would install vents for "cosmetic" reasons. Thanks for your input.
 
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Old 01-12-08, 03:39 PM
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Just to be completely clear, does there appear to be a sheet metal duct behind the return grills, or do they just open into a stud cavity?
 
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Old 01-12-08, 03:41 PM
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They are just open to the stud cavity. No sheet metal anywhere.
 
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Old 01-12-08, 04:45 PM
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The stud cavities may be tied into the return ducting (but sounds like not) - not allowed by most AHJs but still OK in some places. Can you stick a camera into a "return" opening and shoot up and down just to verify that there appear to be no connection?

Home inspectors see just about just about every kind of oversight and omission imaginable, and at an unpermitted flip I could see happening, but in new construction? It's hard even for me to imagine the sequence of events that would allow that to happen at properly permitted and inspected project - the mind boggles at the multiple levels of determined incompetence required on the part of the GC, the HVAC sub and the municipal inspectors...

Not that I doubt that you are seeing what you are seeing....
 
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Old 01-13-08, 03:54 AM
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Thank you Michael.

I will take a couple snapshots and check this morning and post the results. If they do not connect in anyway, I can't begin to imagine how the HVAC contractor will make this right if they are not connected. Thanks again!
 
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Old 01-13-08, 04:33 AM
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My house was built in the early 50"s and at the time gravity type furnaces were still being used. Only the supply side had ducts. The returns used stud cavities and joist runs for the return air which then dropped into the basement and then the furnace would draw the air back in.
But with forced air furnaces, I believe the requirement on new construction is to have metal ducts installed on the return side. This might not be true in some locations.

Its hard for me to imagine that a builder put in returns that go nowhere. Here's how you can tell:
Close off all first floor returns and any in the basement. Close the door leading to the basement. Turn on the furnace blower at high speed. Use a paper cutout, the same size as the opening at the second floor returns and see if it is drawn against the grille. Do not remove the grille when doing this and close each bedroom door.
If the paper is not drawn in against the return grilles in any of the bedrooms, then shut off the blower and the following needs to be checked:

1. Make sure the return filter is clean.
2. With a custom home, you might have a fresh air intake installed and this may be the reason you sense that no air is being pulled down through the second floor cavities. Air will take the path of least resistance and between this and the first floor returns, will draw in the most air. So look for a duct that leads to an outside wall and see if there is a damper anywhere along this duct. See if this can be mechanically adjusted.
3. Or it may be a matter of your first floor returns that were sized too big and need to be corrected.

If you still cannot get any suction at the second floor returns, then its time to hire a hvac technician to examine the installation. If he states the installation is wrong, then the builder deceived you and contact an attorney even if the hvac installation is under warranty.
 
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Old 01-13-08, 12:11 PM
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Wink

[QUOTE Well, I just took the vents off and found they lead to nothing. The white vent just covers a hole in the wall which is lined with studs, but does not connect to the return system like the rest do...hence, no air movement unlike the others in my return vents in my home. /QUOTE]
With the grill off might check and see if the 2X plate on the floor is cut out there.
 
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Old 01-13-08, 03:39 PM
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Well, I'm be damned. I just took pictures facing upward through the cavity and sure enough, there is metal duct work at the top - and obviously leads somewhere. I will need to get in the attic and take a closer look.

RJORDAN392 - Now that you mention "fresh air intake" - I now remember something about my system having that - which explains why those three rooms have a "lighter" draw of air through them then the others upstairs which will pull your shirt off - they draw very well.

Thanks to all of you and your suggestions. Although I can barely sense any air movement in the 3 cavities, I am glad that they are connected to something. Once I get in the attic, I might find they are not connected or have come loose. I don't know much about the fresh air exchange stuff for my system, but would sure think these vents would at least hold a tissue against them while drawing air.

Again, thanks a million everybody ! Jeff. Millersport Ohio.

Thank you Ed and Michael too !
 
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Old 01-14-08, 05:49 AM
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Originally Posted by butch dog View Post
Well, I'm be damned. I just took pictures facing upward through the cavity and sure enough, there is metal duct work at the top - and obviously leads somewhere. I will need to get in the attic and take a closer look.
One of the things you pretty quickly learn at home inspections is never assume anything – I recently stuck a camera (I have a *tiny* little digital camera I carry for just such situations) into what I was sure was a Transite (asbestos containing) duct in a floor slab to see if it was collapsing…. turned out someone had used 2' lengths of clay tile drain pipe for the supply ducts!

Once you get up in the attic a few things to watch for that could be related to your problem: 1) dampers with their controls hidden under insulation, 2) a filter (clogged by long neglect) installed somewhere in the return path and 3) an outside air intake with a misadjusted or malfunctioning damper.
 
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Old 01-14-08, 11:03 AM
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When you check out the ducts in the attic, look in the area where the second floor ducts join together and see if there's a blower fan and a filter built into the main return. There may be a visable cover that needs to be removed to access the blower fan. Or the duct connection may have slipped off the main return. If this is the case, use two small sheet metal screws or a worm clamp to re-attach it. Use foil tape to cover all duct connections.
If there is nothing amiss in the attic, then your next step is to check out the fresh air intake and this may need to be closed off a bit. if it is electrically operated, it may have its own control that allows it to open fully or partially. Look for one of these. It could be located anywhere in the house but its logical location would be in the furnace area. Now be careful about adjusting it because some of this air may be supplying combustion air for the gas hot water heater and the furnace (unless there's a separate air intake for them)and you want to be sure its opened enough.

Now if there is still no improvement and you had already tried closing off all first floor returns for testing purposes, then its time to call on the builders hvac installer to explain the operation and controls of the system and the location of all controls. Tell him you want the return air on the second floor to be fixed.
 
 

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