Damper Theory - HVAC - DIY Chatroom Home Improvement Forum


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

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

Reply
 
Thread Tools Display Modes
Old 01-13-2011, 10:39 PM   #1
Member
 
Join Date: Jan 2008
Location: N.C.
Posts: 418
Rewards Points: 250
Default

Damper Theory


What exactly does a damper accomplish? Is it similar to putting your finger on a garden hose? Decrease flow but increase velocity?

So in an HVAC situation, would a damper decrease air CFM while increasing air FPM?

Advertisement

Earnie is offline   Reply With Quote
Old 01-13-2011, 10:44 PM   #2
Retired from the grind
 
gregzoll's Avatar
 
Join Date: Dec 2006
Location: Midwest - Central Illinois
Posts: 14,431
Rewards Points: 2,524
Default

Damper Theory


Acts as the same purpose as closing a door, or closing a window. Allows for airflow to either travel down the duct, or not. That means the air will go somewhere else, just not out that register.

Advertisement

gregzoll is offline   Reply With Quote
Old 01-13-2011, 10:57 PM   #3
Member
 
Join Date: Jan 2008
Location: N.C.
Posts: 418
Rewards Points: 250
Default

Damper Theory


Ok, I understand the door analogy.

So that means the damper would restrict the CFM of air into the duct but the air that does make into the duct has the same FPM velicity based upon the duct's size (restriction)? Or would the FPM decrease also?
Earnie is offline   Reply With Quote
Old 01-14-2011, 05:33 AM   #4
An old Tradesmen
 
Join Date: Oct 2008
Location: PA
Posts: 26,573
Rewards Points: 4,784
Default

Damper Theory


If a 6 inch round pipe has 100 CFM moving in it with the damper open, the air velocity in the 6" pipe is 509 FPM. If you turn the damper to restrict air flow to 60 CFM, then the air velocity in that 6" pipe drops to 305 FPM.

So no, the velocity does not remain the same if you restrict air flow.
beenthere is online now   Reply With Quote
Old 01-14-2011, 07:47 AM   #5
Member
 
Join Date: Jan 2008
Location: N.C.
Posts: 418
Rewards Points: 250
Default

Damper Theory


Gee, why was that so hard for me to figure out? Makes complete sense now.

Thanks Greg and BT.
Earnie is offline   Reply With Quote
Reply


Thread Tools
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
Dryer vent butterfly damper safe? TryHard Appliances 9 01-17-2011 03:44 AM
Zone Damper Questions rkelly_83543 HVAC 3 04-18-2010 04:52 PM
Damper door on Furnace not opening all the way tro222 HVAC 11 02-08-2010 09:28 PM
Installing Flue Liner thru Damper MikeinBurien Building & Construction 0 10-17-2009 12:39 AM
Zone damper system danstar25 HVAC 10 12-24-2008 02:27 AM




Top of Page | View New Posts