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  1. #1
    Join Date
    Dec 2010
    Location
    Goodyear, AZ
    Posts
    60
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    MUA unit's eefect on a load calculaiton

    Hi Guys,

    I'm a residential system designer working a bit outside of my comfort zone on a commercial load calc. I was hoping to get some advice on this.

    My questions is about Make-up Air units for a commercial Kitchen. Thankfully there has already been a calc done and the equipment for the Kitchen has already been work out. (I'm involved because they are changing the floor plan, which is effecting the mechanical design)

    They have two Greenheck roof exhausts rated for 4,650 CFM
    There is also a dishwasher exhaust rated for 475 CFM
    They have a Captive Air MAU (evaporative) rated for 3831 CFM (Temp diff of intake OAT 108* down to Leaving DBT is 86*)

    I'm assuming the AC RTU economizer can be set to introduce more fresh air to make up what the MAU is lacking.

    My question is does the MAU increase my load for the Kitchen RTU? Or is it a "wash" and the MAU is not part of the AC load calculation?

    Thank you for any help you can provide.

  2. #2
    Join Date
    Jan 2010
    Posts
    16,995
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    Well if your balance is not correct ( not enough makeup ) it will most definitely add load on the RTU's.

  3. #3
    Join Date
    Feb 2016
    Location
    Louisburg Kansas
    Posts
    3,310
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    The reason the MAU is designed for less airflow than the hood exhaust is to keep the kitchen negative. As VTP99 said the RTU's have to make up for the heat load but that extra will come from the other parts of the building.
    If you are not sure get an engineer to take a look.
    No man can be both ignorant and free.
    Thomas Jefferson

  4. #4
    Join Date
    Dec 2004
    Location
    Chicago area
    Posts
    8,074
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    Depends on how cool they want the kitchen. Id get an engineer involved for sure.

    Kitchens are among the toughest spaces to cool.

    If they expect 72 degrees in the kitchen, you’ll need to make that up. Part will come from the other areas, but not all.



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