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  1. #1
    Join Date
    Sep 2013
    Location
    Lafayette, LA
    Posts
    30

    Sealing space around the supply plenum going to the attic

    I have had a professional installer replace my entire HVAC unit. It is an electrical unit installed in a closet in my house. The same closet also has a water heater -- also electrical.

    It turns out that the supply plenum of the new unit is smaller in dimension than that of the old one. The difference is not small. They are both rectangular shaped. On one of the dimension the new unit is about 8in x 24in smaller.

    I am not a handy guy. After the install was complete I happen to walk around admiring my new HVAC. When I flashed my light up, I found that I could see the attic.

    To me this didn't seem like good news. I called the installer. He told me it was part of the building code to ventilate the space because there was a water heater in there. I told him that didn't sound right since I had an electric water heater, and it did do not need ventilation. When I confronted again, he said that he would have the plenum/attic interface sealed *if I wanted*.... but that I'd have to be responsible.

    So folks, I'd like to know what you guys think. I know I am a novice. But this doesn't look like rocket science. From what I have read even small holes in the attic (such as, power for fixtures) can be significant drain. I am talking about a 8"x24" hole linking the conditioned and the unconditioned space.

    While at it, can you suggest how the whole may be sealed. The ceiling is sheet rock.

    Sincerely,

    LafayetteLA

  2. #2
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    68,064
    Electric water heaters don't need combustion air. A piece of duct board can be used, or most any solid material.
    Contractor locator map

    How-to-apply-for-Professional

    How many times must one fix something before it is fixed?

  3. #3
    Join Date
    Dec 2005
    Location
    Cincinnati, Oh
    Posts
    5,042
    Quote Originally Posted by LafayetteLA View Post
    I have had a professional installer replace my entire HVAC unit. It is an electrical unit installed in a closet in my house. The same closet also has a water heater -- also electrical.

    It turns out that the supply plenum of the new unit is smaller in dimension than that of the old one. The difference is not small. They are both rectangular shaped. On one of the dimension the new unit is about 8in x 24in smaller.

    I am not a handy guy. After the install was complete I happen to walk around admiring my new HVAC. When I flashed my light up, I found that I could see the attic.

    To me this didn't seem like good news. I called the installer. He told me it was part of the building code to ventilate the space because there was a water heater in there. I told him that didn't sound right since I had an electric water heater, and it did do not need ventilation. When I confronted again, he said that he would have the plenum/attic interface sealed *if I wanted*.... but that I'd have to be responsible.

    So folks, I'd like to know what you guys think. I know I am a novice. But this doesn't look like rocket science. From what I have read even small holes in the attic (such as, power for fixtures) can be significant drain. I am talking about a 8"x24" hole linking the conditioned and the unconditioned space.

    While at it, can you suggest how the whole may be sealed. The ceiling is sheet rock.

    Sincerely,

    LafayetteLA
    Foam board from lowes.
    All you need is a knife, a tape measure, and a pen.

    Don't worry about the combustion air thing, it's a load of BS.
    "Better tell the sandman to stay away, because we're gonna be workin on this one all night."

    "Dude, you need more than 2 wires to a condenser to run a 2 stage heatpump."

    "Just get it done son."

    Dad adjusted

  4. #4
    Join Date
    Sep 2013
    Location
    Lafayette, LA
    Posts
    30
    Thanks for the responses.

    In the same closet there are also holes in the attic for power supply. They don't look properly sealed either. What's a good way to seal those? Stuff some insulation in it and shut it with mastic?

  5. #5
    Join Date
    May 2004
    Location
    south louisiana
    Posts
    3,185
    no no no...not foam board.
    ductboard. easy to work with, like foam board it cuts with razor knife.
    easy to install from attic side.
    or sheetrock..more difficult to work with, but both have fire ratings.
    over cautious I know...but still.

    holes for power supply. mastic tape. see my reply to your other post
    for details.

    your response from the installer is typical. most are so focused on install
    that issues like this are overlooked.
    is your return air (where you change filter) below the unit in the closet?
    is it sheetrocked? dirty dusty & spiderwebs?

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

  6. #6
    Join Date
    Jul 2000
    Location
    Northern Wisconsin
    Posts
    2,013
    You said the installer was a professional. Sorry, but in my book anyone that would call the installation done without sealing the passage (that they created by reducing the size of the duct work ((is how I read your post))) into the attic doesn't qualify as a professional. IMO
    Use the biggest hammer you like, pounding a square peg into a round hole does not equal a proper fit.

  7. #7
    Join Date
    Sep 2013
    Location
    Lafayette, LA
    Posts
    30
    Quote Originally Posted by firecontrol View Post
    You said the installer was a professional. Sorry, but in my book anyone that would call the installation done without sealing the passage (that they created by reducing the size of the duct work ((is how I read your post))) into the attic doesn't qualify as a professional. IMO

    firecontrol -- I am modulating my language since this is a forum to learn, and not to vent (well, no pun intended). But, I appreciate your formulating the words for me. I am meeting the installation manager tomorrow (Monday) morning. Should it come to it, your opinion would surely help.

    Incidentally, this is one of the leading AC companies "serving" my town. They have a pretty big setup, and been around for over 64 years. (That's the closest hint I'd give. If you are Google savvy you could find it.)

    Should there be someone else following my footsteps, let me also add all of the other installation problems. In a nutshell, even after 64 years in business they appear not to know anything about sealing the air system. There is poor or non-existent sealing starting from return plenum, air flow unit (all the penetrations) and joints, the supply plenum, the plenum and duct joints, flex duct to flex duct joints, and the freon return from the compressor. I can put my finger and feel cold air seeping out.

    I should add until about 36 hours ago I didn't know the names of the various parts, let alone about all the nooks and crannies that need sealing. For me an AC system was one big monolithic entity. I really didn't care to know the parts. After all that's why people specialize. I am thankful for all the folks who have taken the time to write blogs, answer questions on this forum, and make videos. This all sure helped me learn so I can ask intelligible (not necessarily, intelligent) questions on this forum.

    And so very much appreciate the responses from "real" professionals on this board. Its really very much appreciated.

    LafayetteLA

  8. #8
    Join Date
    Sep 2013
    Location
    Lafayette, LA
    Posts
    30
    energy_star_la -- Learned about the Active HERO program by tracing your profile. Shoot, I sure missed out on some rebate. I changed all the doors on my house over the summer (a work done real well), and now the AC. I am sure after the dust is settled, I'd reduce 30% in energy bill. I guess the people I dealt with didn't care to inform me. I see that the Active HERO rater is actively involved in contract, and in a sense, inspect the the work. There is no good coming out of a vendor informing a customer about the program just to have an inspector/rater involved.

    LafayetteLA

  9. #9
    Join Date
    May 2004
    Location
    south louisiana
    Posts
    3,185
    its energy rater La....only correcting the user name because we have
    a member using the name energy star.

    I know well the company of which you speak. have seen their work for years...
    and believe me there are worse companies you could have hired.
    just sad to pay those prices and still have issues.
    a couple of years ago they called me to 'work with them' on existing homes.
    they would refer me to homeowner, because I don't work for hvac companies
    being independent.
    I think I've gotten one referal from them..but over the years I've gone behind them
    & sealed ductwork, returns, and taken over the job where they left off.
    not that they had anything to do with this...just that the homeowner complained
    to LUS, Slemco, Cleco or Entergy enough that they utility provider called me in.

    did you install a high efficiency two stage unit and the plenum started condensating
    excessively? this company had a closed heat pump association meeting about the
    same time they contacted me...and expanded into insulation...they called this
    meeting..it is raining in the attic...due to issues with minimally insulated supply plenums,
    colder air from two state units & our unvented humid attics.

    if you've visited my profile you know my email address is there.
    if I can offer you any advice by email feel free to contact me.
    I hate seeing this kind of mess left behind on any job, but in my backyard...

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

  10. #10
    Join Date
    Sep 2013
    Location
    Lafayette, LA
    Posts
    30
    energy_rater_la -- You scare me. If this one is not the worst, I shudder to think what is worse.

    Well, I had the installation manager visit me with a new crew. Per what I hear they sure think that their sealing was just normal business, and that they are going the extra mile to do what I ask. I had them seal all of the inlets to the air handler, the supply and return plenums, all the attic holes. I even had them open the air handler and seal inside following manufacturer's guideline.

    I missed out on giving specific instructions on one part, and they messed it up. I asked them to seal the refrigerant line, and all they did was to put two zip ties around the cheap foam tube. It is atrocious, I can feel the refrigerant line. Its visible.

    I sent a picture to the installation manager, told him I think the business is incompetent, and also told him that his crew is not welcome back. Sure he has my money. But he is not getting my peace.

    LafayetteLA

  11. #11
    Join Date
    May 2004
    Location
    south louisiana
    Posts
    3,185
    do what you have to do.
    I am sorry to hear that you are having this much issue with your
    install.


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

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