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  1. #1
    Join Date
    Apr 2002
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    Western piedmont of Carolinas
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    1,553

    what does "size for throw" mean?

    Most of my work has been in service, so my training on installation has been limited. I've had classes on manual J and D, the code books and thats it.
    I'm wondering about sizing my supply regesters, and the number of supplies in each room. Where do I find the info for this?

    Thanks

  2. #2
    Join Date
    Aug 2006
    Posts
    11
    Quote Originally Posted by mlock View Post
    Most of my work has been in service, so my training on installation has been limited. I've had classes on manual J and D, the code books and thats it.
    I'm wondering about sizing my supply regesters, and the number of supplies in each room. Where do I find the info for this?

    Thanks
    In order to find this info u need to do load calcs
    and as far as the number of supplies in each room try to get it as low as possable so instead of 2 4x10s use 1 4x14

    what does "size for throw" mean?
    Throw = how far a register will throw the air before it starts to fall

  3. #3
    Join Date
    Aug 2003
    Location
    Fort Worth, TX
    Posts
    11,283
    "Size for throw" would involve finding the supply register's manufacturer data for what cfm is required to be delivered to the register in order to get the full amount of "throw" it was designed for.

    "Thow" is defined as the total horizontal distance the primary air jet travels, from where it emerges from the register to where it reaches terminal velocity, which is often stated as 50 feet per minute.

    "Drop" is defined as the vertical distance the primary jet drops from register to end of throw. Ideally, by the time the jet drops into the "occupied zone", defined as floor level to six feet, and one foot away from walls, it should have mixed with the room air and slowed to terminal velocity so it does not present a draft to occupants within the room.
    • Electricity makes refrigeration happen.
    • Refrigeration makes the HVAC psychrometric process happen.
    • HVAC pyschrometrics is what makes indoor human comfort happen...IF the ducts AND the building envelope cooperate.


    A building is NOT beautiful unless it is also comfortable.

  4. #4
    Join Date
    Apr 2002
    Location
    Western piedmont of Carolinas
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    1,553
    Shophound mentioned the manufacures data, so I looked up hart and cooley. I found a wealth of info. Thanks.
    I would like to get more input on spacing of regesters if anyone can find the time to reply. I also failed to find the pattern of throw for a floor regester. For example on a 421, is the throw measured horizontally in both directions? What about the ceiling height, does it matter? Thanks for the help.

  5. #5
    Join Date
    Aug 2003
    Location
    Fort Worth, TX
    Posts
    11,283
    Quote Originally Posted by mlock View Post
    Shophound mentioned the manufacures data, so I looked up hart and cooley. I found a wealth of info. Thanks.
    I would like to get more input on spacing of regesters if anyone can find the time to reply. I also failed to find the pattern of throw for a floor regester. For example on a 421, is the throw measured horizontally in both directions? What about the ceiling height, does it matter? Thanks for the help.
    You are one who would benefit greatly from reading Manual T, published by ACCA. Although it is subtitled "basic air distribution" for residential, the info it contains satisfied a lot of my own questions regarding residential air patterns/distribution, etc. and I realized instantly how often it isn't being done according to the stated principles. Most ACCA material is supported or derived from ASHRAE data, so it isn't info pulled out from you-know-where.
    • Electricity makes refrigeration happen.
    • Refrigeration makes the HVAC psychrometric process happen.
    • HVAC pyschrometrics is what makes indoor human comfort happen...IF the ducts AND the building envelope cooperate.


    A building is NOT beautiful unless it is also comfortable.

  6. #6
    Join Date
    Jul 2002
    Location
    Yuma, AZ
    Posts
    2,361
    Quote Originally Posted by mlock View Post
    Shophound mentioned the manufacures data, so I looked up hart and cooley. I found a wealth of info. Thanks.
    I would like to get more input on spacing of regesters if anyone can find the time to reply. I also failed to find the pattern of throw for a floor regester. For example on a 421, is the throw measured horizontally in both directions? What about the ceiling height, does it matter? Thanks for the help.
    You are THINKING. Congratulations. You READ. Even better. You UNDERSTOOD what you read. Great!! Our industry needs you and more like you. Keep it up!
    Lynn
    "I have never let my schooling interfere with my education."
    Mark Twain
    More at: http://www.quotationspage.com/subjects/education/

  7. #7
    Join Date
    Aug 2002
    Location
    Office and warehouse in both Crystal River & New Port Richey ,FL
    Posts
    18,836
    Quote Originally Posted by mlock View Post
    Shophound mentioned the manufacures data, so I looked up hart and cooley. I found a wealth of info. Thanks.
    I would like to get more input on spacing of regesters if anyone can find the time to reply. I also failed to find the pattern of throw for a floor regester. For example on a 421, is the throw measured horizontally in both directions? What about the ceiling height, does it matter? Thanks for the help.
    Floor registers for cooling ,need to have a throw of 5 to 6 feet ,to get the cool air high enough in the "occupied " zone,as cool air falls.

    Too little throw with them and temp will be much higher when standing.

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