Replacing 6" ducting with 4"


  #1  
Old 09-24-08, 09:04 PM
R
Member
Thread Starter
Join Date: Sep 2008
Location: Washington State
Posts: 2
Upvotes: 0
Received 0 Upvotes on 0 Posts
Replacing 6" ducting with 4"

I am taking a wall out and need to reroute the heating ductwork to an upstairs bedroom. All the exising ductwork is 6" or the flatter 7" that runs up a stud wall. I only have room to run a 4" duct and will tye off the existing original 6" ductwork from the basement. is this ok to do or will the airflow into that bedroom be significantly reduced. Any response would be appreciated....Thanks
 
  #2  
Old 09-25-08, 04:22 AM
airman.1994's Avatar
Member
Join Date: Dec 2005
Location: VA
Posts: 5,491
Upvotes: 0
Received 8 Upvotes on 8 Posts
You will be reducing the air flow by alot!
 
  #3  
Old 09-25-08, 06:47 AM
Gunguy45's Avatar
Super Moderator
Join Date: Dec 2007
Location: USA
Posts: 19,281
Received 7 Upvotes on 7 Posts
rw
Just to give you a basic idea of the reduction....4" has a opening area of 12.6 sq in, 6" has an area of 28.3 sq in. Big difference! You'd need at least 2-4" ducts to even come close. And thats just the area of the opening, there's things that need to be taken into account like losses from the proportionally greater inside surface area of the duct wall in the smaller stuff.
And what air is coming through the 4" will be higher velocity, so you may get noise issues as well.
 
  #4  
Old 09-26-08, 09:05 AM
M
Member
Join Date: Jan 2008
Location: Tennessee
Posts: 438
Upvotes: 0
Received 0 Upvotes on 0 Posts
"will the airflow into that bedroom be significantly reduced."

As previously stated, yes
 
  #5  
Old 09-30-08, 08:29 AM
J
Member
Join Date: Sep 2008
Location: USA
Posts: 108
Upvotes: 0
Received 0 Upvotes on 0 Posts
Dont do it. We are currently re-doing out duct to make it bigger on out 5-ton system becuase the original house desing is too small (duct work).
 
 

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