Interpulating System Capacity Charts
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  1. #1
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    Interpulating System Capacity Charts

    It amazes me when I look at how these manufacturers are rating their equipment yet when you look at the capacity charts they are off of the tonnage by up to 1500 BTU combined.
    I am sizing a Rheem unit and have noted that they are rating at an 80 degree indoor and 95 degree outdoor. I need my capacity at 75 indoor and 91 degree outdoor design. I think we are supposed to have a multiplier to interpulate these numbers but I am not seeing one.
    Does anyone know how this is done? I have 2.5 tons of ductwork and am off by 2,000 btu on sensible load of being able to use that size, even though my total is under 30,000 by 4,000 btu's. Rheem is calling 28,800 a 2.5 ton unit.
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  2. #2
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    I am sizing a Rheem unit and have noted that they are rating at an 80 degree indoor and 95 degree outdoor
    And there numbers would be at an 67*IDWB. That would be standard AHRI design numbers, just not reality.
    Post there extended rating chart and your design numbers and I will walk you through it ( unless someone else beats me to it).
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  3. #3
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    Also remember. Depending on you sensible heat ratio

    According to ACCA manual S. Excess latent capacity can be used towards sensible load.

  4. #4
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    Quote Originally Posted by tlj000 View Post
    Also remember. Depending on you sensible heat ratio

    According to ACCA manual S. Excess latent capacity can be used towards sensible load.
    Its 1/2 of excess latent, but none the less imporant to remember!
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  5. #5
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    Sorry guys, I didn't get an email that this post had been replied to.
    I think half the excess latent will bring me in, if that is all there is to it. I was told the chart can be interpulated. Here are the numbers
    The unit specs are 28,600 total capacity, 21,650 Sensible, 6,950 latent.
    My load calc came up to 22,818 Sensible and 3952 latent. So half the excess would be 1499 + 21,650= 23,149.

    JIMJ, I don't know if that was enough info or not. I don't know how to post a chart here, but that is pretty much what the chart gives.
    In case that isn't enough info, and you feel inclined, the chart is on the Rheem site. This is the Cube style unit, model 13JPL30A01 matched to a RHSLHM3017JA air handler.
    Thanks
    The main thing is to keep the main thing the main thing!

    If "the grass is greener on the other side", it likely has been fertilized with Bull$hit!

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