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  1. #1
    Join Date
    Jul 2008
    Location
    New Jersey
    Posts
    3

    replace Round with Rectangular need help

    Hi new member with a question. May sound anal but I want to change out round ducts with rectangular. HVAC contractor my builder hired ( I was still asking for estimates and pricing out different systems at the time) came in and without my consent and ran 14 -16 inch round ducts down the middle of the 10 feet garage ceiling effectively making them just over 8 feet after being framed out and covered with sheetrock (firecode). This is a small project. We are building a three car garage with an apartment above (approx. 900 square feet). I really don’t like losing all this headspace. Because my builder allowed HVAC guy to do the work and HVAC guy won't change out the round to rectangular ducts without additional expense to me, I paid him but have told him I don't think I will use him for the rest of the installation. PS not being difficult, this HVAC contractor also said we didn't need to do a heating or cooling load calculation. He said has been in the business long enough and can size systems with out all those calculations. He said the old "rule-of-thumb" of 800 SQ FT per ton works good enough. I had to demand he do the calculations and they proved the unit he was planning to install was oversized. It was a high end 2 stage Heat Pump unit and even in the worst weather the chances were very remote I would ever use the second stage. So my question is how I can find a table or formula that can help me see what sizes I need to use in rectangular ducts to replace the round ones, and any issues or concerns anyone has regarding this. Would prefer the programs or software or help be reasonably priced and easy to use. Thanks for any help or suggestions you can offer.
    Walt

  2. #2
    Join Date
    Mar 2005
    Location
    burlington county n.j.
    Posts
    9,761
    tell the builder to make it right or get his @ss off the job.......


    should have never paid for something you did not agree to.
    losing 2' of a 10' ceiling is not acceptable.

    14" round equal to 8 x 22, 16 round equal to 8 x28

  3. #3
    Join Date
    Jul 2008
    Location
    New Jersey
    Posts
    3
    Hi t527ed, My builder gave him the go ahead so I feel I'm liable. I paid him cause I'm building in a small comunity in Tenessee and it appears there are a lot of "friendships" that have developed down there and if I want to get the appartment finished I have to be careful about what fights I want to fight.

    Thank you for the two sizes. Where can I find more of them for other sizes. The guy did at least go through the motions of doing a good job. He starts the main trunk with what appears to be the 16 inch round and each time he runs a flex line to the room he cuts the round down a size or two. No dampers so no way to balance the system later but he does drop the size of the trunk.

    thanks

    Walt

  4. #4
    Join Date
    Jun 2008
    Location
    South,Tx
    Posts
    331

    discussion with contractor .........

    don't you hated when you (HO) are trying to save every inch of space and they just go ahead and do it !
    Maybe they did not "hear you"(HO) when it was time to start the Job and you had set some kind of boundaries for the limited space !
    Matt 7:12 The Golden Rule
    "Do for others what you would like them to do for you. This summary of all is taught in the law and the prophets.

  5. #5
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    68,603
    Dampers at the take offs aren't needed when the duct is being drywalled in.

    The qustion isn't what size rectangle duct is equal to 16" round,its what size duct do you really need?
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