HVAC Duct Sizing - HVAC - DIY Chatroom Home Improvement Forum

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


Thread Tools Display Modes
Old 01-28-2013, 08:15 PM   #1
Join Date: Jan 2013
Posts: 1
Rewards Points: 10

HVAC duct sizing

Just need to check to see if I'm right regarding my thoughts for a furnance install in my shop. Here goes.

Shop is 30 x 56 18 ft walls pole barn, metal skin,lightly insulated
Furnace 80%+ 96K btu, 4 ton blower. factory fan set med high (approx 1700 cfm no AC, Im installing horizontally midway long wall 8 feet off the floor.

I have same size insulated ducts Im using as return air and supply plenum, both are 20 X16 Hey they were free.

Return Ill have two 12 inch flex from the "plenum" running along trusses down opposite wall no grills. one run about 40 feet the other 50.

Supply will have two "mains" off supply using flex. 10inch 90elbow to 4ft flex to 10inch tee reduced to 8inch to 8 ft of flex to 8inch tee reduced to 6inch then 8ft of flex to 6inch tee capped. next "main" is 8inch elbow 2ft of flex to 8inch tee reduced to 6inch to 6 feet of flex to tee capped.

Need a little check to see if this works. Thanks


Blueraider is offline   Reply With Quote
Old 01-28-2013, 09:11 PM   #2
An old Tradesmen
Join Date: Oct 2008
Location: Somewhere
Posts: 34,591
Rewards Points: 8,168

Returns and supplies too small.

Returns for their length should be 16". But you could get away with 14".

Supplies should also be 14" to start with, then maybe an 8" supply with the trunk continuing in 12 then another 8" supply, and then the trunk 10" and let it be the last supply.


beenthere is offline   Reply With Quote

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
Repaired HVAC duct. What did I do wrong? What did I do right? SingleGuy HVAC 12 07-07-2012 02:12 PM
Replacing Duct Tape Used on HVAC Ducts yarrick19 HVAC 5 06-17-2012 11:29 PM
Bathroom Exhaust Fan Duct Sizing Lyndon HVAC 6 02-06-2012 07:35 AM
Duct sizing bigdee HVAC 0 11-05-2010 09:04 PM
Properly Sealing HVAC Duct Work craymer45 HVAC 5 11-06-2008 08:47 PM

Top of Page | View New Posts


Search Engine Friendly URLs by vBSEO 3.6.1