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How to size an evaporative cooler

Discussion in 'Growing Areas' started by Jon, Mar 31, 2009.

  1. Jon

    Jon Mmmm... bulbophyllum...

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    The Kuul Pad system I created for cooling my GH in the summer doesn't work very well. Sure, it lowers the temps enough, but it also kills the RH to the point that I only have 15% at times (orchids don't like that). So this summer, I've decided to get an evaporative cooler. My only issue is that I'm not sure how to appropriately size a unit. Here's what my stats are:

    Volume of the GH: 800 cubic feet, +/- 10%
    Shade cloth: ~50%
    Outdoor RH: 5-30%
    Maximum temps outside: 110f
    Maximum desired GH temps: 90f

    What are your thoughts on how I should determine the capacity of a unit? I don't want one that is so large that it cycles on and off every 5 minutes, but I also don't want one that is on all day.
     
  2. Jon

    Jon Mmmm... bulbophyllum...

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    I'm not looking for a specific answer, but maybe someone would chime in with things I should consider...
     
  3. Clark

    Clark Gator Member

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  4. Jon

    Jon Mmmm... bulbophyllum...

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    That's good Clark. Thank you. Any idea how I'd factor in the effects of solar heat?
     
  5. Armando

    Armando Hobbyist gone wild

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  6. Clark

    Clark Gator Member

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    No idea how to factor in solar heat. I though they gave you some ideas on size of the area you're trying to cool.
     
  7. Marni

    Marni Well-Known Member Staff Member Supporting Member

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    With a small greenhouse, I would try for a cooler that would circulate 2 to 3 times the cibic feet of the greenhouse when set on high. The small volume heats up much faster than a large one. You can always use it on low if the volume is too great.
     
  8. T. migratoris

    T. migratoris Active Member

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    This is a great thread Jon. I've had the same question for some time now. I did some calcs on my own a while back & when I tried to match up to a unit I couldn't find one small enough.
     
  9. JonP

    JonP all that Supporting Member

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    I'll be curious too to see if there is a suitable unit for a small greenhouse.
     
  10. Forrest

    Forrest Really Neat

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    JonP, you need to come visit me sometime.
     
  11. Jon

    Jon Mmmm... bulbophyllum...

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    It seems like the big question mark is the effect of solar intensity. I am going to go with a 2800 CFM unit unless someone here can convince me to try otherwise.
     
  12. Forrest

    Forrest Really Neat

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    that looks like a good one Jon. Little smaller than mine box wise. No idea about my fan.
     
  13. Jon

    Jon Mmmm... bulbophyllum...

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    It's the smallest of the window types. I was considering the 3500 CFM unit, but that almost seems like too much.
     
  14. Forrest

    Forrest Really Neat

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    the wind that comes out of mine is surprisingly gentle.
     
  15. JonP

    JonP all that Supporting Member

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    Indeed.
     
  16. suss16

    suss16 New Member

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    Don't know if this helps... I recently built a 10 x 16 attached GH. I use a 75% shade cloth in the summer and have a large cedar tree that filters much of the midday sun in summer. I installed (manufacturer reccomendation) a FrigiKing FS350 cooler. It has kept my GH 85 degrees or below during it's first summer. Max temps in Norfolk, VA was the low 100's. But we have high humidity that impacts the efficiency of evap cooler, as compared to Denver.

    Just some info...
     
  17. Jon

    Jon Mmmm... bulbophyllum...

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    Thanks suss16. Firsthand info is invaluable.
     
  18. Armando

    Armando Hobbyist gone wild

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    Make sure your outlets (shutters and/or vent openers) match the capacity of the cooler.
     
  19. Jon

    Jon Mmmm... bulbophyllum...

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    I was going to use an 18" square suhtter. It should be sufficient for 2800 CFM.
     
  20. T&J San Antonio

    T&J San Antonio New Member

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    One other thing to consider is the amount of calcium you have in your water. Calcium build up the evap pads considerably reduces the desired cooling effect. In Colorado, I doubt you have that problem but down here it is a factor to deal with.

    just tom