Duct work material options

Greetings to everyone,
Background:
I have been doing some research on environmentally friendly ductwork installations and have seen many arguments against using uncoated duct board. The disadvantages range from a breeding ground for dust mites and mold to inhalation of micro fiber particles and formaldehyde.
As I have a newborn in my household and my duct board boxes and lined flex hose are all black on the inside, I am looking to replace the entire ductwork system. My ductwork is in the attic and will primarily be used for cooling a small 1300 sq/ft Florida home.
The entire current system is all lined flex hose connected with triangular duct board junction boxes and terminated with duct board register boots.
Questions:
1. What are my options for replacing the junctions, plenum, and register boots with non fibrous duct board material?
2. If it's sheet metal, is there a way to insulate them just on the outside up to R6?
3. My longest current flex hose run is about 11 feet. Is it possible to design a system using only flex hose that is properly sized?
Example:
             10 Ft.          |===============|Boot 1|      || 9Ft. || Plenum =======|Triangle Junction|          ||     ||         ||     ||      5Ft.||     |============|Boot 2|         ||        11 Ft.         ||      |Boot 3|
Thank you in advance for any suggestions,
Dmitry
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
It's tough to align these ascii characters just right :)
Example:
             10 Ft.          |===============|Boot 1|      || 9Ft. || Plenum =======|Triangle Junction|          ||     ||         ||     ||      5Ft.||     |============|Boot 2|         ||        11 Ft.             ||      |Boot 3|
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Dmitry:
Get the ducts cleaned, replace your furnace filter with a new one when it gets dirty, and don't worry too much. Your baby will do fine. New dads are always this way. :)
Cordially yours: Gerard P.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Gerard,
It's too late. I already ripped everything out. The boots were all black on the inside anyway, so I am not sure if that can even be cleaned.
Thanks, Dmitry
snipped-for-privacy@gannon.edu wrote:

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
FWIW, if it was my house, I would have left it alone till December. Now, you are not only without a/c (unless you have a couple of window unit to use meanwhile), but you get to work in a 130+ deg attic also. Regardless, to answer your questions- sheet metal all the way is the best way to go. It can definitely be wrapped outside to R6, though for your area I would try to get R8 wrap. The easiest, quickest and cheapest route is a new ductboard plenum and new R8 flex ducts, with new sheet metal register boxes. You can either get new ductboard triangles, or use sheet metal Tees or Wyes with the flex. That is not the best way to go, but around here (San Antonio) that is what about 99% of the houses built in the last 20+ years have, so while not ideal, it will certainly work if properly designed. Good luck Larry
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Thanks Larry. I am to the point of no return now, so I'll work during the nights when it's cooler. The flexduct and sheet metal tees will work nicely.
The only problem with prefabricated metal boxes is that my register cutouts are about a inch from the joists and the flange will not fit. Also, the boxes I have seen are lined with the fiberglass exposed ductboard.
lp13-30 wrote:

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Site Timeline

HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.