Need help with ducts or whatever

Problems related to residential installations.

Need help with ducts or whatever

Postby dragonkx » Wed May 23, 2012 1:12 am

The bottom half of my house gets poor heat and cooling, from bedroom 2, 3, and 4. Do I need more ducts or maybe another return because of length of hallway, or what?
*.*/albums/mm422/dragonkx/scan0001.jpg
sorry for poor picture
dont know if you can see the link but the **** is p h o t o b u c k e t . c o m
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- Need help with ducts or whatever

Postby heatseeker » Wed May 23, 2012 7:55 am

The or what would be time to buy a window unit or portable ac to help with lower half cooling load, unless you want to do some serious remodeling. I assume your house is two stories by the description you gave.
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- Need help with ducts or whatever

Postby dragonkx » Wed May 23, 2012 8:19 pm

no just one story house as seen in picture, and i prefer no window AC, i dont want to install 3. there is air coming through the registers, just not enough, its a 4.5 ton unit
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- Need help with ducts or whatever

Postby heatseeker » Thu May 24, 2012 8:14 am

cant see photo.
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Postby dragonkx » Thu May 24, 2012 7:19 pm

well its probably a 4 ton unit, and dont want to contact a contractor, because they charge, and i plan to do it myself, i know how, just not sure what i need. having a hard time putting website link up
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Postby heatseeker » Fri May 25, 2012 10:04 am

"I know how" and "I just don't know what I need". Two conflicting statements. Good luck.
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- Need help with ducts or whatever

Postby dragonkx » Sat May 26, 2012 2:02 am

what i meant is i know how to run the ducts etc, the manual labor. Im just not sure how much airflow i need more, or wheather it requires an additional return
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Postby Freon » Sat May 26, 2012 11:32 am

Tell us more. How many return ducts and what size? How many supply ducts and what size? Metal or flex ducting? Are there reductions in duct size as you more from the air handler? Your first step is to draw a picture of your entire duct system with all duct dimensions and lengths. Then we can help more effectively.
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- Need help with ducts or whatever

Postby dragonkx » Sun May 27, 2012 11:14 pm

a drawing is already posted of my duct system, but this website doesnt allow . c o m etc. so part of it is **** out. kinda explained in my first post
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Postby Freon » Fri Jun 01, 2012 2:41 pm

Some rough -
For each ton of cooling you need ~400 cfm of air flow. Check your furnace/air handler for the blower chart. Look at the speed tap setting (low, med or high) and then the corresponding air flow for 0.2 "WC
Once you know what air flow your system should be delivering you can calculate if your ducts are adequate. The return air flow and the supply air flow should be equal.

Approximations for metal -
6" diameter *
8"*
10"*
12"*
14"*
Any 90 degree elbows subtract 10% so a 6" line with 1@ 90 degree elbow would deliver ~ 90 cfm

For flex duct I'd reduce all the above by 20%
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