Moving duct work - interior partitionl removal project

Hey all,
I have a kitchen and living room separated by a load bearing wall that has 3 ducts and 1 cold air return running thru it. I'd like to remove the wall and put in a beam. The new beam and the wall removal I can deal with, but, moving duct work is going to be a new challenge.
Currently there are 3 ducts coming off the main trunk line (in the unfinished basement ) at separate spots in intervals of 16 inches (so the lines fit up the wall cavities) they run west @ 6 feet off of the trunk line before they turn up thru the wall I want to remove. I'd like to take out the ducts, and run 1 large line off the main trunk line. this new line would exit the main trunk line 1 foot north of where last of the 3 current ducts located. (trunk line runs N/S) I'd then remove the majority of the existing wall, then this new line will run 6 feet from the trunk line then turn up next to the "stub" of the remaining wall. Then when the new line reaches the ceiling turn it back south in a ceiling bulkhead to rejoin the remaining duct work that runs thru the floor of the second floor. The current ducts all open into the same room which currently gets too much air with all the vents open.
I understand that running angles at 90' will really cut down on air flow but, I don't think I have much of an other option. My question is, If I remove the 3 lines and consolidate them, should the sq footage of a cross section of the new square duct be larger / smaller or the same size as the sum of the 3 existing ducts.
ie. given 3 pipes at 6 inch round then (6*6 / 2) *3 = 54 inches so new square line off the trunk line should be 6x9 or so.
thanks in advance for any advice.
Dave
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zephyr wrote:

Pardon me for asking, but I am only trying to keep someone out of trouble and I don't know your qualifications.
You seem unsure of moving ducts, but feel good about removing a load bearing wall. Do you have experience as an engineer? Guessing on this job is not a good thing.
I am not sure what others will recommend here, but I suggest employing a HVAC professional that will do the math for you and make sure your ducts as planed and air handling capacity you have will handle it. No getting it right now, can be very expensive later to correct. Almost as expensive as the damage caused by making a mistake on the load bearing wall.
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Joseph Meehan

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He definetely needs a pro, and likely changes to his furnace and AC like a bigger blower motor, if its even possible. he might have to upgrade to a high speed small diameter duct system, whatever the changes are going to cost big bucks:(
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Gentlemen,
I appreciate your concearn for my safety and well being, I do not have experience as an engineer, however, I do have a good friend who is an architect and he should be able to come up with the correct size beam for me. I do have experience as a framer, so, the wall portion of the job is not going to be difficult. (just plain old hard work) however, I'd love to know if I should over size the extension to the trunk line, or not in order to get sufficient air to the upstairs bedroom.
For those interested in the bearing wall part of my project, it is an 11 foot wall with a doorway currently in at the south end of the wall (wall runs n/s) , I want to expand the "doorway" to be 8+ feet wide. regardless I will be pulling permits, so whatever mistakes I make *should* be caught by an experienced pro. I'm just hoping to skip having to redo / repair any work.
Dave

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I think most of us here dont want to see anyoone bring down a cieling or worse:( Such sad events can and do occur:(
a good friend had a issue like yours, they opened the wall with a couple pillars where the ducts ran from basement to upstairs and installed a wall and counter about 3 feet tall.
IMHO you need to get a estimate from a heating contractor...
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Been out of school over 60 years so someone may correct this. WW
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Warren,
your right, thanks for the correction
Dave
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