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AC from Hell

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  • clammy
    clammy Member Posts: 3,111
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    space pak/unico

    having installed a few unicos and no spacepak the one think i do know is that space pak recommends a minum of 8 outlets per ton which is why i stick to unico which only requires 6 per ton mimuin .8 per ton and the home looks like swiss chease.On the last few unicos i have used april air hepa filter systems and have had no promblems but i have also sized my return ducts for .05 static and used a the rule of 1 squre foot of return grill for each ton of a/c which keeps your returns quite.Not to make anybody sound bad but did the installation co have experence installing this type of system?Did the installers follow the manafactors requirement on where outlets should be cut into the main supply truck did they size the supply duct to the manafactors outlines?Unico guidelines and installation booklet gives you alot of suggestion and recommadations on proper installation pratices which i have always followed and have really had no promblems related to noise ,airflow evap coil freezing or capacity . Peace and good luck clammy
    R.A. Calmbacher L.L.C. HVAC
    NJ Master HVAC Lic.
    Mahwah, NJ
    Specializing in steam and hydronic heating
  • William Faust
    William Faust Member Posts: 168
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    Here is a chart of what SpacePak requires for Minimum and Recommended Number of Fully Open Outlets:

    Nominal Tonnage - AH Unit - # Outlets
    2 2430 12
    2.5 2430 14
    3 3642 17
    3.5 3642 19
    4 4860 26
    5 4860 26

    This data is detailed on page 7 of the online SpacePak document titled Application Manual for Central Air Conditioning and Heating Systems.

    The installing contractor does 500 installations per year. The problem appears to be that they focus on the top line and do jobs quickly without much analysis. How do they still manage to get so much revenue? They spend a lot of money on marketing.
  • William Faust
    William Faust Member Posts: 168
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    Okay, I think that you are telling me that increasing the number of outlets INCREASES static pressure in all of the ductwork with the result that the CFM at each outlet DECREASES. Do I have that correct?

    I have also just realized that SpacePak's "Standard CFM" of 850 CFM at 1.5" W.C. for their 3642 apparently assumes zero leakage and the minimum number of fully open outlets (3-ton condenser with no jet tubes longer than 15'). Air leakage is apparently sort of like having unintended additional outlets with associated higher static pressure and lower CFM.

  • Techman
    Techman Member Posts: 2,144
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    John

    Increasing the # of outlet let more air out of the main trunk so the static press drops,decreasing CFM out of each outlet.
  • Eugene Silberstein 3
    Eugene Silberstein 3 Member Posts: 1,380
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    Thanks for that info John

    Thank you sir.
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