Sizing cold air return

Reply

  #1  
Old 12-14-07, 10:53 AM
Member
Thread Starter
Join Date: Dec 2007
Posts: 2
Received 0 Votes on 0 Posts
Sizing cold air return

I have 2 gas furnaces in our house . I just added a great room 20x25 with 3 4x12 (7 inch) heating vents and was wondering if a 16x8 cold air return would suffice or should I go larger. The trunk for the cold air return is an 8 x 12 trunk that is existing but could be changed . there are 3 6 x 8 returns existing in other parts of the house.

I also have a 15 x 17 room that has 4 4x12 (7 inch) heating vents off of the 2nd furnace ,and was planning on running a 16x8 trunk line for the returns and a 14x8 trunk for heat. would the 16x8 return be enough for this ???
 
Sponsored Links
  #2  
Old 12-14-07, 04:28 PM
Ed Imeduc's Avatar
Member
Join Date: Aug 2002
Location: Mountain Williams Missouri
Posts: 18,389
Received 0 Votes on 0 Posts
Wink

Out of the box here. But 3-- 7" = 405 CFM so to get that back to the furnace you need about A 9 " pipe or say a 8X8 . Dont make a furnace have to work to get air back to it. But this all goes back to how or what the other duct work is like
 
  #3  
Old 12-14-07, 05:10 PM
Member
Thread Starter
Join Date: Dec 2007
Posts: 2
Received 0 Votes on 0 Posts
thanks

The other ductwork is not great they put cold air returns in every room that are 6 inch(3 of them) running thru 6 " flex back to the main furnace.I am working on changing them out also. Thank you very much for the info
 
Reply

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


Thread Tools
Search this Thread
Display Modes
 
Ask a Question
Question Title:
Description:
Your question will be posted in: