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 06-11-2008, 08:20 PM   #1
Member
 
Join Date: Jun 2008
Posts: 68
Rewards Points: 0
Share |
Question

Replacing 30 yr old duct... couple questions


On a hot day in Houston my house will barely get below 80 if we are lucky. Among the problems are just flat out old ducts. Besides replacing the ducts, I was thinking about converting my main trunk line to rigid or metal duct, i've heard it flows better.

My question is: How would this throw off the balance of my system? I ask because I've got about 4 lines coming straight off the plenum to various rooms, then a trunk line goes about 25 feet to the other side of my house to the kitchen, formals, breakfast area, and laundry room. Would a more efficient trunk on one side reduce flow on the other side?

Also, the splitters look like they are made from ductboard taped together, I've got 2 splitters with 4 and 5 ducts coming off each one and they leak awfully. What is a good replacement for these? Is aluminum tape appropriate for sealing ducts?

bigburb is offline   Reply With Quote
Old 06-11-2008, 09:29 PM   #2
Member
 
Join Date: Jun 2008
Posts: 152
Rewards Points: 0
Default

Replacing 30 yr old duct... couple questions


fiber board ducts if un lined release fiberglass into the air and is illegal in13 states the ones that care whats in the air the best install is whats called a reducing plenum depending on the size of the system you start with 12 or 14 inch round ducts insulated with 3 inch wrap every 2 or 3 branch lines you reduce the trunk by 2 inches each branch should be 6 ,7,8 r-8 flex attatched with a sadle collar with volume dampers
this method is the right way it will maintan equal static pressure and volcity and allow you to balance the system perfectly
no flex run should be over 15 feet
every reducer should have a short peice of flex of the smaller size to prevent the reducers from breaking
all of these connections should be made with screws and zip ties silver tape at all insulation seams

geo fan is offline   Reply With Quote
Old 06-12-2008, 06:22 AM   #3
Member
 
Join Date: Jun 2008
Posts: 68
Rewards Points: 0
Default

Replacing 30 yr old duct... couple questions


Wow you know your stuff. If not ductboard, what would I build the reducer plenums out of?
bigburb is offline   Reply With Quote
Old 06-12-2008, 06:10 PM   #4
Member
 
Join Date: Jun 2008
Posts: 152
Rewards Points: 0
Default

Replacing 30 yr old duct... couple questions


use pre fab round metel duct its cheaper then square duct and the install is faster less time in that 130+ attic
geo fan is offline   Reply With Quote
Old 06-09-2009, 06:32 PM   #5
Newbie
 
Join Date: Jun 2009
Posts: 5
Rewards Points: 0
Default

Replacing 30 yr old duct... couple questions


The old duct work is sweating in a couple of spots causing drywall issues in a couple of spots on the ceiling. I've been in the attic, extremely tight and access is limited to address the areas giving me headaches, and added insulation in some areas. On the coast in Texas with this humidity causes many problems.
I'm considering replacing all of the metal/'insulated' duct with flex. Any guidance or suggestions would be appreciated.
Thanks.
bohica24 is offline   Reply With Quote
Old 06-09-2009, 06:48 PM   #6
Member
 
Join Date: Jun 2008
Posts: 68
Rewards Points: 0
Default

Replacing 30 yr old duct... couple questions


I've heard you should have runs longer than 25', though I was not able to avoid it and my house cools just fine. Have you tried an insulating jacket on your metal duct?
bigburb is offline   Reply With Quote
Old 06-10-2009, 09:09 PM   #7
Newbie
 
Join Date: Jun 2009
Posts: 5
Rewards Points: 0
Default

Replacing 30 yr old duct... couple questions


Are you saying that the runs should be 25ft. or longer in this type of climate, does that reduce sweating? The runs are already insulated, but in a couple of places they sweat anyway. More wrap, jacket?? I'd rather not replace all the ductwork if there is a better solution.
Thanks.
bohica24 is offline   Reply With Quote
Old 06-11-2009, 05:26 AM   #8
Member
 
Join Date: Jun 2008
Posts: 68
Rewards Points: 0
Default

Replacing 30 yr old duct... couple questions


I meant to say shouldn't have runs longer than 25', this causes too much resistance in the line to effectively deliver air, or cool air at that. Like I said, it can be done, I did it, its just not recommended if you can avoid it.

bigburb is offline   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
replacing rectangular duct with 6" pipes peso HVAC 4 06-05-2008 08:43 PM
Tiling my kitchen floor, couple of questions Yeti Flooring 14 03-27-2008 09:15 PM
couple questions about installing phone jacks joeyboy Electrical 31 10-09-2007 02:26 PM
couple questions about painting on different surfaces joeyboy Painting 3 08-19-2007 02:33 PM




Top of Page | View New Posts

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