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Thread: Manual J and Manual D?

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  1. #1
    Join Date
    Dec 2011
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    Manual J and Manual D?

    Quote Originally Posted by HVAC_HUSKER View Post
    He would need to do A manual j and manual d for the whole house including addition... Not just adding duct and some dampers.. The whole dust system will more than likely need to be redesigned or you may need to upgrade system size. This is what manual j will tell you. Then you will have a option to use manual dampers and balance system properly or you do a complete zoning system... You can't do both.. But as long as its designed properly then system should thrive..
    what is manual J and manual D??

  2. #2
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    Jan 2004
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    manual J is a method of determining a structures heat loss and gain. manual D is a method of determining the total equivalent length of a duct system to determine what friction rate loss to use on a duculator.

  3. #3
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    Jan 2009
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    Both are critical to properly sizing, designing and installing a complete HVAC system. Anything short, is just varying degrees of guesswork or a matter of simply throwing it together.

    IF the transmission died in your car, would you want them to use a mfg specific service manual and procedures, or just throw it together because they are "all about the same".

  4. #4
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    Aug 2009
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    A couple of books from the bible of the HVAC world.

  5. #5
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    Jun 2005
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    kls-ccc; Great Statement...

    Quote Originally Posted by kls-ccc View Post
    A couple of books from the bible of the HVAC world.
    When doing the Manual J heat-gain/heat loss, look at fixing those areas that allow too much gain or loss; as if you can reduce the equipment size that will help the existing duct system to work better.

    Though you'll still need to run a Manual D so you know the system is going to work properly. Far too many never check airflow at all...

  6. #6
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    Dec 2011
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    Thread Starter
    thnx guys,..this site is helpin me lot...a couple of mnths earlier i was nt even knowin d HVAC full form, somebudy askd me n i told him it mayb high voltage alternating current..hehe...bt now m learning day by day n also implementing it my project

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