Damper requirements in HVAC ducting


  #1  
Old 04-18-09, 02:11 PM
G
Member
Thread Starter
Join Date: Apr 2009
Location: Bolingbrook, IL
Posts: 49
Upvotes: 0
Received 0 Upvotes on 0 Posts
Question Damper requirements in HVAC ducting

I am working on finishing my basement and I have reached the HVAC ducting part of the project. The existing ducting mostly runs through the basement so I think all I need to do is tap into the main trunk line with some 6" round duct runs.

My question is this:

I have noticed that the existing 6" duct runs each have dampers in them. Am I required to put dampers in the new duct runs that I install in the basement? Does having a register where the duct enters the room fulfill this requirement?
 
  #2  
Old 04-18-09, 03:05 PM
HVAC Mech.'s Avatar
Member
Join Date: Jun 2008
Location: Rocky Hill, CT. USA
Posts: 220
Upvotes: 0
Received 0 Upvotes on 0 Posts
Dampers are usually installed in the take-offs from the trunk line for balancing the air flow of the whole system. Having them at the trunk dampens some of the noise from the velocity increase when the damper opening is decreased.
You could use the diffuser located dampers if you don't mind the noise.
I imagine you'd be using the AC more for dehumidification than cooling in the basement.
Couldn't you just mount the diffusers right onto the supply duct?
Of course you'll have to mount a return diffuser in the return duct, to utilize the existing filter.
Does this system have the capacity for the increased load (small as it may be)?
TomBeer 4U2
 
  #3  
Old 04-18-09, 04:04 PM
G
Member
Thread Starter
Join Date: Apr 2009
Location: Bolingbrook, IL
Posts: 49
Upvotes: 0
Received 0 Upvotes on 0 Posts
Thanks for the quick reply!

I don't mind a little bit of noise. The ceiling in the basement is not all that high right now (about 7' 9" or so), so I would like to put in a solid drywall ceiling and not a drop ceiling. This means that unless I put access hatches for each damper then I won't be able to adjust them after the ceiling is up.

I'd rather not mount the diffusers right on the supply duct because I want improve the air flow in the basement from where it is right now. I am trying to get the supply diffusers on the opposite side of the room from the return. I had not thought about putting a damper on the return side, I suppose I should do that as well.

I am pretty sure that the system can handle the load. There is already a single supply vent in the basement and the entire basement is underground. I plan to put up pretty good insulation on all the exterior walls as well so I don't think it will require much air to heat and cool the space. The temperature does not vary down there much as it is.
 
  #4  
Old 04-18-09, 05:57 PM
D
Member
Join Date: Jan 2008
Location: New Jersey
Posts: 76
Upvotes: 0
Received 0 Upvotes on 0 Posts
Fyi

I'm assuming that all of your runs (rest of house) have dampers, Depending on the layout of your house, you might adjust them seasonally to maximize comfort.

Once you put your ceiling up, they're out of reach.

Delta
 
  #5  
Old 04-19-09, 07:52 AM
HVAC Mech.'s Avatar
Member
Join Date: Jun 2008
Location: Rocky Hill, CT. USA
Posts: 220
Upvotes: 0
Received 0 Upvotes on 0 Posts
Originally Posted by griffon02345
I had not thought about putting a damper on the return side, I suppose I should do that as well.
I assume 'damper' is a typo. You should install a return grill before the filter rack, in the return duct.
Tom Beer 4U2
 
  #6  
Old 04-19-09, 08:21 AM
G
Member
Thread Starter
Join Date: Apr 2009
Location: Bolingbrook, IL
Posts: 49
Upvotes: 0
Received 0 Upvotes on 0 Posts
I was definitely going to put in a return grill. Do I need to put in one that I can adjust the openings on? Or do I just need to put up a plain return grill with no adjustments?
 
  #7  
Old 04-19-09, 04:02 PM
HVAC Mech.'s Avatar
Member
Join Date: Jun 2008
Location: Rocky Hill, CT. USA
Posts: 220
Upvotes: 0
Received 0 Upvotes on 0 Posts
No, dampers are never installed in the returns.
Tom Beer 4U2
 
  #8  
Old 04-19-09, 08:19 PM
G
Member
Thread Starter
Join Date: Apr 2009
Location: Bolingbrook, IL
Posts: 49
Upvotes: 0
Received 0 Upvotes on 0 Posts
Thanks,

I've got the main return line done then and I'm working on the supply ducts. I bought some simple dampers that I can install inside the 6" round ducts. Working above your head installing these ducts along the ceiling is no fun!
 
 

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