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  1. #1
    Join Date
    Apr 2013
    Posts
    24

    Air quality issues after some recent attic HVAC work. Pics of work enclosed.

    I recently had some HVAC work done in my attic to help alleviate higher temperatures in my second floor home office. As part of this process they installed a hot air return in my office, moved the office supply duct closer on the trunk to the air handler to supposedly increase air flow in office, and also added a return box for my returns to go into.

    I have noticed since we have done this work that my kids and my allergies have been bad when we are upstairs and am concerned that maybe some of the unconditioned air from the attic is making it into AC. We already did a mold/indoor air quality test and that came up clean. Hell it could just be allergies, but I have never really had any.

    So I went up into the attic and noticed some things that I want to make sure is right.

    Where the office supply flex is attached to the main duct there is a stream of cold air being shot out into the attic. I know that shouldn't happen and needs to be fixed, but would that also pull in attic air? You can see a photo of this here:

    http://www.flickr.com/photos/8860377...57634649951991


    I also see the return box, but not sure if its installed correctly. From what I can tell, they only moved the main upstairs heat return to the return box and connected my office return directly to the air handler. I didn't have much room in the attic to check that 100%. Should there be insulation around the return box. From what I have been told the all ducts are supposed to be insulated as per code, but am not sure if a repair needs to be done to code. An example picture is:

    http://www.flickr.com/photos/8860377...57634649951991


    I also took out my office return filter and looked into it and noticed that part of the duct is inside the black plastic box, but a portion is not. Could this be sucking air in from wall voids? You can see what I am talking about in the picture below. Look inside the red circle.

    http://www.flickr.com/photos/8860377...57634649951991


    Finally, I see on one side of the return grill black plastic box that I see dry wall through some of the holes. Should the black plastic box lip have gone down further to cover any wall gaps? Not sure if this matters or not, but you can see what I am talking about in this picture.

    http://www.flickr.com/photos/8860377...57634649951991


    Now I know nothing about HVAC, so not sure if I am worrying about nothing, but I am just trying to rule out all possible causes.

    Pictures of all the work can be found in this flickr set:

    http://www.flickr.com/photos/8860377...7634649951991/


    Thanks in advance.

  2. #2
    Join Date
    Apr 2013
    Posts
    24
    Can anyone tell me if there should be insulation around the return box?

    They are coming tomorrow to take a look at things and do not want to be a pain in the ass asking for things that are not necessary.

  3. #3
    Join Date
    Oct 2004
    Location
    So Cal
    Posts
    3,557
    Return plenum is probably insulated inside the sheetmetal.
    Removing blower door should verify this.

    Ducts should be sealed & have no cold air escaping & yes, it can pull unfiltered hot air into air stream.

    On return grille- they should remove the grille & seal the box to drywall. Then those little holes & gaps in grille are less of an issue.

    On duct in wall- your pic w/ red circle. Hard to see what's going on here but in any event, it must be sealed so it doesn't draw from wall cavity.

  4. #4
    Join Date
    Apr 2013
    Posts
    24
    Quote Originally Posted by precision hvac View Post
    Return plenum is probably insulated inside the sheetmetal.
    Removing blower door should verify this.

    Ducts should be sealed & have no cold air escaping & yes, it can pull unfiltered hot air into air stream.

    On return grille- they should remove the grille & seal the box to drywall. Then those little holes & gaps in grille are less of an issue.

    On duct in wall- your pic w/ red circle. Hard to see what's going on here but in any event, it must be sealed so it doesn't draw from wall cavity.
    Thanks precision hvac. I am almost 100% sure the return box they added is not insulated on the inside. I saw it right before they installed it and there was no insulation at all on the inside.

    As for the return grille they definitely did no sealing when they installed it as I was in my office working while they did it. They just cut a square and inserted it in.

    Thanks for the info.

  5. #5
    Join Date
    Aug 2003
    Location
    Fort Worth, TX
    Posts
    11,358
    Supply air ducts leaking into an attic can cause dirty air to be sucked into your house through walls, floors, etc.

    Return air ducts leaking in an attic can suck in dirty attic air. When the attic gets hot, you might detect that "hot attic smell" when your a/c system runs.

    You should get every area that caught your attention sealed with mastic. I would call the person back who did this work and insist they seal it.
    • Electricity makes refrigeration happen.
    • Refrigeration makes the HVAC psychrometric process happen.
    • HVAC pyschrometrics is what makes indoor human comfort happen...IF the ducts AND the building envelope cooperate.


    A building is NOT beautiful unless it is also comfortable.

  6. #6
    Join Date
    Apr 2013
    Posts
    24
    Sound good. Thanks for all the advice. They will be coming today and I will show em everything that should be resolved.

    I assume for the return box they should mastic and tape each edge of the box and then insulate the box from the outside?

    I definitely have detected the "hot attic smell" in certain pockets upstairs.

    Thanks again for the info.

  7. #7
    Join Date
    May 2004
    Location
    south louisiana
    Posts
    3,240
    ugh...cellulose insulation.
    think about this...when they cut the hole for the new supply duct, cellulose particles
    fell inside the house. cellulose is ground newspaper treated for with borate.
    it makes a very fine 'dust' that enters the house through every unsealed hole.
    and they just made new holes.

    because you can't seal around supply boxes on all sides from the attic..
    esp with cellulose,
    I've learned to do it from inside the house.
    see attached picture.

    I use Hardcast brand #1402 mastic tape. not the stuff they used on
    your new duct...mastic tape...1402 hardcast.

    sealing supply boxes to sheetrock as in the pic is the only way
    I've found that lasts and holds the box tightly in place
    when supply grill is re-installed.

    1402 will seal all of the areas you mention as long as surfaces
    are clean & dry.
    check inside returns...take your existing supply grills down &
    seal all of these supply boxes too.

    the house I'm currently working in has cellulose & a child
    with asthma. today I shop vac'd half a bag of cellulose out of
    the return air.

    sealing supply & return leaks is in your best interest.

    best of luck.
    Attached Images Attached Images  
    The cure of the part should not be attempted without the cure of the whole. ~Plato

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