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  1. #1
    Join Date
    Aug 2007
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    273

    Retrofit system and duct size--do I have to be supper concerned

    We are planning to retrofit or existing system with an infinity gas furnace, infinity A/C unit and new coil in our forced air home that is from the 1930's. My question is: in general do most homes have adequate size ducts to handle such a retrofit or is duct size a major issue. Since my contractor did not spend too much time checking out the duct sizes in our house, I assumed that duct size was in general was not much of an issue--- now I am concerned Worried in Washington dc.Thanks for your reply and sorry for any double posts.
    Last edited by ron3637; 11-10-2007 at 09:58 AM. Reason: clarification

  2. #2
    Join Date
    Aug 2004
    Location
    North Richland Hills, Texas
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    Duct sizing is a critical issue, and existing duct systems, especially older heating ducts, are rarely even close to adequately sized for the new equipment.
    If more government is the answer, then it's a really stupid question.

  3. #3
    Join Date
    Aug 2002
    Location
    Office and warehouse in both Crystal River & New Port Richey ,FL
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    Quote Originally Posted by mark beiser View Post
    Duct sizing is a critical issue, and existing duct systems, especially older heating ducts, are rarely even close to adequately sized for the new equipment.
    Ditto,ask about it before the install!They need to look closely,test the existing duct static pressure,etc..

  4. #4
    Join Date
    Aug 2007
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    273
    Other than replacing the ducts what can be done to correct for there size. Also is a static pressure test difficult to do? thanks

  5. #5
    Join Date
    Oct 2007
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    Milwaukee,WI
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    Quote Originally Posted by ron3637 View Post
    Other than replacing the ducts what can be done to correct for there size.
    Nothing really.


    Also is a static pressure test difficult to do? thanks
    It's easy for any professional.
    ___________________________

    Chicago is an indian word for stinky!!!!!!
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  6. #6
    Join Date
    Aug 2007
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    273
    If nothing can be done what is the difference? What would you recommend if the test comes back negative? thanks?

  7. #7
    Join Date
    Jan 2004
    Location
    Lancaster PA
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    66,758
    Something can always be done about it.
    The question is how much will it cost.

    Some times its a simple fix, and some times its not.
    Get your ducts tested/checked first.
    Contractor locator map

    How-to-apply-for-Professional

    How many times must one fix something before it is fixed?

  8. #8
    Join Date
    Oct 2007
    Location
    Milwaukee,WI
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    1,066
    Quote Originally Posted by ron3637 View Post
    If nothing can be done what is the difference?
    The only thing that can really be done is to have new ducts put in.
    ___________________________

    Chicago is an indian word for stinky!!!!!!
    -supertek65

  9. #9
    Join Date
    Mar 2007
    Location
    Myrtle Beach, SC
    Posts
    2,919
    Sometimes bigger ducts is the answer. Sometimes low loss fittings can provide enough improvement.

    We do load calculations, most existing units in my area are too big. The ducts may be too small for your existing system, but if you install a smaller system, the ducts may now be adequate.

    But if you don't test the ducts before the changeout, you are really screwed if you find out they are too small after the changeout. Then you have to do the whole thing over again.
    Remember, Air Conditioning begins with AIR.

  10. #10
    Join Date
    Aug 2002
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    Quote Originally Posted by Lash View Post
    The only thing that can really be done is to have new ducts put in.

    Improved fittings,turning vanes,adding an additional return trunk ,etc.,can often solve high static issues.

    Parallel supply trunks can also solve issues.

  11. #11
    Join Date
    Oct 2007
    Location
    Milwaukee,WI
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    Quote Originally Posted by dash View Post
    Improved fittings,turning vanes,adding an additional return trunk ,etc.,can often solve high static issues.

    Parallel supply trunks can also solve issues.

    3 of the 4 things you listed qualify as 'new duct'.


    ___________________________

    Chicago is an indian word for stinky!!!!!!
    -supertek65

  12. #12
    Join Date
    Aug 2002
    Location
    Office and warehouse in both Crystal River & New Port Richey ,FL
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    "Originally Posted by ron3637
    Other than replacing the ducts what can be done to correct for there size.

    Nothing really."



    Quote:
    Also is a static pressure test difficult to do? thanks

    It's easy for any professional.
    __________________

    Your comment above lead me to believe that you were stating ducts need to be replaced,sorry for my mistake.

    And yes some of what I suggested is adding new ducts and fitting ,just not wholesale replacement of an existing duct system,to solve a static issue.

  13. #13
    Join Date
    Oct 2004
    Posts
    149
    If it's anything like my house (built before A/C was invented) then the duct size is adequate for heating, but not for A/C.

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