Using Flex Duct For Return. - 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 11-13-2011, 09:31 PM   #1
Member
 
Join Date: Nov 2011
Location: Ontario, Canada
Posts: 38
Rewards Points: 25
Default

Using flex duct for return.


I am thinking of adding a second return duct to our house, mainly to reduce drafts and even out temperatures. System is a 3 ton heat pump, ecm air handler with 1200cfm max flow.

Our existing and only return is at one end of house and starts from 20x25 ceiling mounted filter/grille and elbow, reducing to 20x14 metal duct about 25ft long and terminates with sweep elbow leading into box at entrance to horizontal air handler. All of this is in unheated attic in Canada.

What seems the best option for the additional return will require a take-off off the existing sweep elbow, a 45 elbow, a straight run of about 12 ft. and a 90 elbow before entering new ceiling filter/grille boot.

Using pre-insulated flexible duct (12 or 14in) would likely be easiest install. Otherwise if metal is used, sealing joints and insulating will have to be done in place in a very tight area.

My questions:
- Is flex duct suitable for a return duct where pressure could be -0.5"wc ?

- Are there different grades of flex duct? Different materials ? Some of the stuff in box stores doesn't look too good!

- Insulation will need to a minimum of R12. Is flex duct available with R12? If not, would it be practicable to add a second layer or perhaps use uninsulated duct and pre insulate?

If I do this, I will be helped on a weekend by a tinbanger friend who works days on commercial HVAC jobs.

Any help in getting me up to speed would be appreciated!

Advertisement

lakeresident is offline   Reply With Quote
Old 11-14-2011, 05:16 AM   #2
An old Tradesmen
 
Join Date: Oct 2008
Location: PA
Posts: 26,525
Rewards Points: 4,688
Default

Using flex duct for return.


Flex duct doesn't come in an R12 version, so you will have to wrap it.
Its fine to use for a return.

Advertisement

beenthere is online now   Reply With Quote
The Following User Says Thank You to beenthere For This Useful Post:
lakeresident (11-14-2011)
Old 11-14-2011, 09:12 AM   #3
Member
 
Join Date: Nov 2011
Location: Ontario, Canada
Posts: 38
Rewards Points: 25
Default

Using flex duct for return.


Quote:
Originally Posted by beenthere View Post
Flex duct doesn't come in an R12 version, so you will have to wrap it.
Its fine to use for a return.

Did some Googling. Found one type called Quiet Flex that has a pressure rating of negative 0.5" and then Hart & Cooley with negative 0.75" . With almost new filter, we see -0.25", but this should drop with extra return. Seems -0.5" would be OK, but 0.75" better.
lakeresident is offline   Reply With Quote
Old 11-14-2011, 10:56 AM   #4
I'm Your Huckleberry
 
Join Date: Mar 2011
Posts: 5,884
Rewards Points: 2,270
Default

Using flex duct for return.


Quiet Flex is owned by Goodman and made locally, like Goodman, here in Houston.

Anywho...
Doc Holliday 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
AC Flex Duct - Suspend above attic insulation or lay it on top? fritzycat1 HVAC 13 08-17-2011 11:19 PM
Planning on New duct work..any feedback... kilosos2 HVAC 28 01-26-2011 10:21 AM
Jenn-Aire Downdraft - OEM flex duct required? Dwizzo Appliances 0 10-09-2010 05:35 PM
Metal duct or flex? smokey982 HVAC 6 08-06-2010 07:20 AM
Flex Duct Advice ssporty21228 HVAC 4 07-23-2008 09:28 PM




Top of Page | View New Posts