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  1. #1
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    Mar 2019
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    Exclamation Warehouse Air Conditioning Help Needed-Load Calculations, and What AC Unit? Help

    Can a pro help me calculate my true BTU usage needs for Air Conditioning an old warehouse space?

    I'm about to sign the lease on a 1000sq ft warehouse space. I can use some help trying to do a load calculation for air conditioning, and some opinions on the types of AC units I'm considering. Help with Load Calculations, figuring out BTU requirements, and some feedback on a few units I researched will be helpful.

    Here are some details:
    -In the Northeast, so summers get HOT (Use NYC as a comparison). 3 to 4 solid summer months of regular air conditioning. As a note, this does NOT need to be cooled to what a house would since it is a warehouse. Cooling the temp to 75 would be more than enough, the idea is just enough to maintain comfort.
    -1000 Sq Ft (Room is about 50ft x 20ft)
    -13 Foot Ceilings-Windows
    -Entire East Wall is old single pane crappy windows. I'd say they are 9 feet tall from the ceiling, and span the entire 50 feet. So there is a lot of glass.
    -The space faces the East, but there is another building in front directly East, so it gets sun from around 9:00am until about 1:00pm if I had to guess.
    -Top floor of a building, and the roof above has a black roof
    -We have about 10 fluorescent lights overhead, of which most won't be used regularly. So 500 Watts Maximum
    -2 People typically working in the space

    Its a wide open concrete rectangle basically with a wall of old windows. The ceiling looks like thick concrete, its an old war time factory that was made to withstand bombs being dropped on the roof so it may block heat, or radiate im not sure. Lots of ceiling mounted wiring so I dont think insulating the ceiling is an option. There are others on the same floor that dont have AC and simply sweat it out, Id rather not do that if I can help it.



    Load Calculations for AC:
    Using various calculators, I'm getting anywhere from 30,000BTU's to about 70,000BTU's. Since this space is very old, faces partially into the sun, and the windows are horrendously old, I should be erring on the side of higher than lower load calculations.

    Can someone help calculate my true load calculation and figure out what I really need? Would 35,000BTU unit cut it? Would a 60,000 BTU unit?

  2. #2
    Join Date
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    What equipment, if any, will be in the space?
    I havent failed. Ive just found 10,000 ways that wont work. - Thomas Edison

    Its not whether you get knocked down, its whether you get up. - Vince Lombardi

    "In this house we obey the laws of thermodynamics" - Homer Simpson

    Local 486

  3. #3
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    Mar 2019
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    Thread Starter
    Quote Originally Posted by rider77 View Post
    What equipment, if any, will be in the space?
    Thanks for the reply. Not too much equipment. A computer, and it has about 10 overheat fluorescent light fixtures, but we don't expect to use them all in the summer since we get plenty of natural light. The windows face East, but there is a building between us and direct east, so we get sun about an hour or two after it rises, and it stays with us until about early afternoon indirectly.

    Keep in mind this is a warehouse, so it doesn't need to be office cold. If it were to maintain in the mid to high 70's that would probably be fine.

    Is 60,000BTU required for this space? More? Less? Seems like all the calculators I see either say 3 ton, or 5 ton, with a few stating around the 60,000BTU range. Any feedback appreciated.

  4. #4
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    Aug 2002
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    Without a lot more info we cant say.

    Get a contractor to take measurements and advise!

  5. #5
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    Mar 2019
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    Thread Starter
    Quote Originally Posted by pecmsg View Post
    Without a lot more info we can’t say.

    Get a contractor to take measurements and advise!
    What measurements are needed? I have nearly all the room measurements.
    -Room is 50X20
    -Ceilings are 13 feet tall
    -East Facing Windows are roughly 9 feet tall, by 50 feet long between all the panes.
    -Equipment wattage usage is minimal
    -Only 1 or 2 people per time in the space
    -1 double steel door goes into space from a shared hallway
    -Top floor of 5th floor building
    -Ceiling very thick concrete (Not sure how thick but supposedly very thick) with a black tar roof

    What else can I share to help you all help me with this calculation?

    I appreciate you all helping me out.

  6. #6
    Join Date
    Sep 2005
    Location
    Atlanta GA area
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    I would put a 2 stage 5 ton AC unit in there...

    Why???

    The unit will run at about 3.5 tons in low stage... which will give you lots of cooling capacity.
    When it gets HOT... the unit will go to high stage and give you more capacity.
    Match it to a VS gas furnace with something in the 125-135K capacity... maybe a little less if you use a condensing furnace.

    The VS furnace will help with a dehum cycle... which makes the area feel better.

    Oh yeah... and add some ceiling fans... stirring the air helps!

    Remember: installation is more important than equipment brand, so choose your contractor wisely!
    GA-HVAC-Tech

    Your comfort, Your way, Everyday!

  7. #7
    Join Date
    Mar 2019
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    Thread Starter
    Quote Originally Posted by ga-hvac-tech View Post
    I would put a 2 stage 5 ton AC unit in there...

    Why???

    The unit will run at about 3.5 tons in low stage... which will give you lots of cooling capacity.
    When it gets HOT... the unit will go to high stage and give you more capacity.
    Match it to a VS gas furnace with something in the 125-135K capacity... maybe a little less if you use a condensing furnace.

    The VS furnace will help with a dehum cycle... which makes the area feel better.

    Oh yeah... and add some ceiling fans... stirring the air helps!

    Remember: installation is more important than equipment brand, so choose your contractor wisely!
    Landlord will not allow a roof install, or air conditioner hanging out the window. So i'm stuck with either some type of portable unit, or building some type of contraction that can be pushed up to a large window opening that must stay flush (No overhang).

    Someone suggested I get 3 or 4 (14000BTU) portable air conditioning units with dual pipe setup. Think this would actually work? Those units are around $450 each, if I had to install 3 or 4 of those that would be easy. Would they actually do the job is the question though.

    Not sure what I need to do at this point...

  8. #8
    Join Date
    Aug 2002
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    Southold, NY
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    Quote Originally Posted by MagicNobody View Post
    Landlord will not allow a roof install, or air conditioner hanging out the window. So i'm stuck with either some type of portable unit, or building some type of contraction that can be pushed up to a large window opening that must stay flush (No overhang).

    Someone suggested I get 3 or 4 (14000BTU) portable air conditioning units with dual pipe setup. Think this would actually work? Those units are around $450 each, if I had to install 3 or 4 of those that would be easy. Would they actually do the job is the question though.

    Not sure what I need to do at this point...
    Good luck

    Portable units are worthless

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