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  1. #14
    Join Date
    Nov 2011
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    East Side
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    Quote Originally Posted by theoldscroll View Post
    20% is a lot when you're trying to cool a place,as now desired sometimes 70, when it's 100 out with 58% humidity.
    I was referring to the OP of shutting down all equipment for a building. with no air movement, or mechanical cooling, I would say there is a possibility for high humidity causing problems.

    I think raising the set points would be a better option, rather than killing everything.


    I'm sure there are a lot of "energy management" companies creaming their panties right now with the MASSIVE amount of money they are "saving" their customers.

  2. #15
    Join Date
    Apr 2020
    Location
    Garner NC
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    471
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    In my experience it’s depended on what the blue prints say or the local mechanical inspector. If it had a kitchen in it there always was a MUA unit.
    Residential installation was 3-4” with a damper, Commercial Splits and HP was 4” to 18” with a manual damper at the return section for “recommended specs” you needed to basically (at a minimum)match the exhaust “bathroom” fans.

  3. #16
    Join Date
    Apr 2020
    Location
    Garner NC
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    Maybe you can get away with 402.2 ...minimum at 4%

  4. #17
    Join Date
    Mar 2015
    Location
    Medford, N.Y.
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    6,653
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    4% of Fresh Air ? Where is that info coming from?

    Try "Ventilation for Control of the Work Environment" by William A. Burgess, Michael J. Ellenbecker & Robert D. Treitman... 476 pgs.

    It is a Good Read.

  5. #18
    Join Date
    Apr 2020
    Location
    Garner NC
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    471
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    In the photo document that's shown lower right corner, you can see it...section 402.2 its very short..

  6. #19
    Join Date
    Mar 2015
    Location
    Medford, N.Y.
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    6,653
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    Quote Originally Posted by Unlimited1 View Post
    In the photo document that's shown lower right corner, you can see it...section 402.2 its very short..
    Tks. I did not have my screen on "full screen" so the print was real small. lol.
    But, I think that says 4% of floor space. I'm not sure how that converts over to % of indoor air,as in CuFt %.

  7. #20
    Join Date
    Apr 2020
    Location
    Garner NC
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    471
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    It did not mention how old the building was also...air leakage alone in it should be considered a factor..I have also seen concrete floors wick water through into the buildings mainly at the floor seams. a moisture meter confirmed it.. Separate dehumidifiers was installed with the condensate tubing being drilled through the exterior walls and sealed as they was the worst rooms. It was pointed out the building also had a lower base elevation than the rest..I joked about ripping out the parking lot around the building to re-pitch the water away from it..I also got into trouble for joking about it, lol..Some people just don't understand. lol

    I do use a Flir E4 to show air leakage...It one of the best tools in my arsenal...especially ductwork leaks...and checking vent temps. I also found a few flex connections that blew off in the dropped ceiling that way...the customer was really happy especially because no one else checked it..

  8. #21
    Join Date
    Apr 2007
    Location
    Amarillo by mornin'
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    1,034
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    I would bring in enough just to pressurize the space/building. Along the lines of 71CHOPS is saying about humidity, if it gets high enough for long enough the building management/owners are going to be pissed when they see all of their ceiling tiles sagging. They are going to go from patting themselves on the back, to kicking their own butts.
    "It's not that I'm smart, it's that I stay with the problem longer”
    Albert Einstein

  9. #22
    Join Date
    May 2020
    Location
    Austin,TX
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    31
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    I would say its a risk, any building, even a vacant one, needs circulated air, fresh air exchange, and moderate temperature control to prevent extreme temp shifts. Not sure theres a standard for Unoccupied buildings, could be wrong. Sick building syndrome is a serious concern and mold is an issue if humidity gets out of control.

    When get called in to mothball a building I typically set the air handlers set point to 75, schedule them 12 hours on, 12 hours off, Typically I like see 2 air changes an hour to keep the building fresh, I adjust the outside air to something reasonable, most air hanlders 10%-15% outside air of total output volume.

  10. #23
    Join Date
    Apr 2020
    Location
    Garner NC
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    471
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    I’m used to seeing 80-85 for cooling and 55 for heat when unused ..The tstats are Honeywell 8000 with fans set for circulate ( the fan randomly comes on)

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