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Thread: Sweating Plenum

  1. #1
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    Default Sweating Plenum

    Buyer was supposed to close on this Chicago condo conversion tomorrow: no hot water, leaks under every sink, construction debris in hydro-therapy tub, no appliances installed etc., the inspection was “suspended” pending unit completion to the point where complete inspection was possible.

    Anyways... this was a small 1 BR/1BA garden apartment, installed was a 40,000 BTU 50 gal water heater and 40,000 BTU GFAF - could not get a look at the condenser up on the roof as it was storming throughout the entire inspection.

    In addition to everything else you can see in the pictures (and some stuff you can’t) the exterior of the plenum above the coil was *covered* in condensation which was running down the exterior of the A-Coil housing and into the furnace (sorry it's not clearer in the pictures, but that "peened" appearance is all beaded water) – I’ve never seen anything like it, humidity was high and there was a 25 degree different between interior and exterior temperatures, but still… So I was wondering about the possibility of mis-sized/mismatched furnace/blower/A-coil.

    An HVAC tech is going to have to look at this furnace in any case – there has obviously been drywall dust and chips and other debris going down the open combustion air intake (no manual on-site, and I've not yet found one on-line, so I don't know if the manufacturer allows drawing combustion air from the interior) and the secondary drain is not plumbed, etc. and I’ll note the excessive condensation.

    But would others here have/report specific suspicions of other problems based on the sweating?

    -----------

    Inspecting in the city is always interesting: supposedly this place passed inspection - you gotta' love the kitchen plumbing and that smoke alarm (that *is* a smoke - not CO - alarm).

    I still haven't discovered a way to ding these stairs as hard as I feel they deserve... they just offend my sense of common sense - perhaps Mr. Peck can help me out on that one... though if they keep that door open, they may just float away (did I mention it was raining... HARD... during this inspection?) - and yes, that extension cord appeared to be live.

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    Last edited by Michael Thomas; 08-23-2007 at 08:40 PM.
    Certified Master Inspector CMI

  2. #2
    Join Date
    Mar 2007
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    Default Re: Sweating Plenum

    Was the plenum lined? Was it in the conditioned space?
    If the unit had not been on long enough to lower the interior humidity and temperature levels, then the condition might have just been temporary. If not, maybe duct wrap might be needed.
    Mis-match is a possibility on components, but construction dust and improper installation is also a possiblity.

    Jim Luttrall
    www.MrInspector.net
    Dallas, Texas

  3. #3
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    Default Re: Sweating Plenum

    Conditioned space; utility area off the kitchen. Don't know if the plenum is lined. The painters had been in the apartment all day, presumably the AC had been on all day as well (they did not speak enough English for me to determine for certain).


  4. #4
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    Garland, TX
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    Default Re: Sweating Plenum

    For starters the tiled step risers are uneven/unequal first elevation transition from wood to tile surface is a riser although minimal not equal to the other two in height (riser height shall be no difference greater than 3/8")
    The wood hand rail will allow a 6" sphere at the lower diagonal and is not continuous over the bottom tread
    Wood treads are not deep enough 10" minimum
    http://buildingcodes.jocogov.org/doc...#37;20Book.pdf

    How is that wood support column in front of the wood stairs anchored to the offset pier and is pier properly sized for it's purpose?

    I thought the AHJs were cracking down on porch, deck, balcony in your area???

    Last edited by BARRY ADAIR; 08-24-2007 at 12:33 AM.
    badair http://www.adairinspection.com Garland, TX 75042 TREC # 4563
    Commercial-Residential-Construction-EIFS-Infrared Thermography
    life is the random lottery of events followed by numerous narrow escapes

  5. #5
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    Default Re: Sweating Plenum

    Berry

    The exterior porch steps are a common element - I "observe" these "incidental" to the inspection, and note them in the report along with my standard boilerplate re: association responsibilities, but don't "inspect" them (couldn't as a practical matter, on a building this size in the time available); my reporting responsibility lies with those tiled interior stairs.

    And given the 4 riser rule there is no requirement for a handrail, the drop off at the side isn't high enough to require a guardrail and the landing is deep enough to be compliant, so it appears that I'm left with that short "riser" at the floor.

    OTOH, common sense tells me that those stairs are an accident waiting to happen.

    I will FYI my opinion those stairs would be safer with - at a minimum - a handrail on the wall - it just vexes me that other than the riser they appear to be compliant, which is why I'm asking if anyone sees anything else.

    As for the City's take on those exterior stairs (let alone the fact that there is is several inches of standing water outside the back door of a below grade unit) - there are various aspects of this conversion that lead me to believe that either the municipal inspectors have not been there lately, or are just too busy to do their job properly.


  6. #6
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    Default Re: Sweating Plenum

    Your observation that the painters had been there all day may lend a clue about the sweating. You could have very high humidity levels that could overwhelm the a/c unit just due to these activities. Start with a high humidity level when the painters get there then add buckets of latex (water based) paint and there goes the ball game.
    Jim

    Jim Luttrall
    www.MrInspector.net
    Dallas, Texas

  7. #7
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    Default Re: Sweating Plenum

    Jim,

    Good point. Thanks


  8. #8
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    Default Re: Sweating Plenum

    Quote Originally Posted by Michael Thomas View Post
    I still haven't discovered a way to ding these stairs as hard as I feel they deserve... they just offend my sense of common sense - perhaps Mr. Peck can help me out on that one...
    Michael,

    Barry did a good job of addressing the stairs.

    Regarding the sweating of the plenum, it is a 'supply' plenum and I thought they had to be insulated, even when installed in conditioned space (otherwise, you will lose your conditioned air - heating or cooling - before it reaches the far end of the duct work).

    If the plenum is not insulated, all that rain and leaving the doors open off and on (would not even take leaving the door open all day) and you will have that plenum all beaded up like that. I would expect that to happen anyway if it is not insulated - cold metal plenum + warmer moist air = condensation on the cooler surface.

    Jerry Peck, Construction / Litigation Consultant
    Construction Litigation Consultants, LLC ( www.ConstructionLitigationConsultants.com )
    www.AskCodeMan.com

  9. #9
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    Jul 2007
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    Chicago
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    Default Re: Sweating Plenum

    Hi Mike..
    Another good recomendation for the stairs ,and posibly why they look funny may be lack of nosing.

    "Nosing. Stair treads should extend slightly past the face of the riser. This is
    Called the nosing. Nosing is used to make certain that the back of your foot
    clears the face of the riser".
    Though we are not code inspectors ,this is off the city site.
    I also note that with hinges on the right side ,one needs to step towards that drop.
    Condensation in this weather would not concern me.
    I would right up that the blower was used during construction,which can void a warranty.
    Every cond rehab or new construction I see the blower is full of cr-p.

    Last edited by Bob Elliott; 08-24-2007 at 12:39 PM.

  10. #10
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    Frankfort, KY
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    Default Re: Sweating Plenum

    Quote Originally Posted by Jerry Peck View Post
    Michael,

    Barry did a good job of addressing the stairs.

    Regarding the sweating of the plenum, it is a 'supply' plenum and I thought they had to be insulated, even when installed in conditioned space (otherwise, you will lose your conditioned air - heating or cooling - before it reaches the far end of the duct work).

    If the plenum is not insulated, all that rain and leaving the doors open off and on (would not even take leaving the door open all day) and you will have that plenum all beaded up like that. I would expect that to happen anyway if it is not insulated - cold metal plenum + warmer moist air = condensation on the cooler surface.

    Not real sure about national code but in our area if the ducts are in a conditioned space they don't have to be insulated.

    Myself I don't care for this due to the reasons you pointed out, I want the BTU's getting from the equipment into the building envelope not the basement.

    That being said we insulate our ducts in conditioned spaces.

    Measured Performance more than just a buzzword

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