Go Back   DIY Chatroom Home Improvement Forum > Home Improvement > HVAC

CLICK HERE AND JOIN OUR COMMUNITY TODAY...IT'S FREE!

Reply
 
Thread Tools Search this Thread Display Modes
Old 02-22-2010, 08:54 PM   #1
Newbie
 
Join Date: Feb 2010
Posts: 7
Rewards Points: 10
Default

Are the duct sizes wrong also?


My furnace is in the basement with a reducing plenum duct design. If I have that bit of terminology correct, I 'd like to see if the trunks and branches were designed correctly. I'm sure I'm way off, but should the cross section area of the branches be less than or equal to the area of the trunk?

For example, the far end of the supply trunk measures 8x14= 112 sq. inches. The four 6" round branch area is also 112 sq. inches. The next trunk step larger measures 20x8 for 160 sq. inches, but has eight 6" round branches that total 224 sq. inches. The trunk with the a/c evaporator measure 20x20 I believe. So, is the 112 sq." measurements a coincidence, or is the first trunk too small for the number of supply branches?

I wasn’t sure if the trunk size and number of branches were equally proportionate, or purposely undersized to create pressure. Thanks again.

turfgrass is offline   Reply With Quote
Old 02-22-2010, 10:58 PM   #2
An old Tradesmen
 
Join Date: Oct 2008
Location: PA
Posts: 26,021
Rewards Points: 3,708
Default

Are the duct sizes wrong also?


A 20X8 duct moves more air then 8-6" round ducts do at the same FR.

A 10' long section of 20X8 duct has a total surface area of 46.66 sq ft.
8-10" long sections of 6" round duct has 124.8 sq ft of surface area. So they would be far more resistive to air flow. And move less air.

beenthere is online now   Reply With Quote
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
help w/ duct sizes & new supply locations palex1915 HVAC 0 10-13-2009 08:52 PM
Duct sizing C44 HVAC 3 03-23-2009 05:24 PM
Flex Duct Advice ssporty21228 HVAC 4 07-23-2008 09:28 PM
Condensation in Wall: Can I Seal a Dryer Duct With Caulk? xquercus HVAC 5 07-01-2007 03:33 PM
duct sizing Stu HVAC 2 12-22-2006 06:36 PM




Top of Page | View New Posts

Copyright © 2003-2014 Escalate Media. All Rights Reserved.