Which of these 4 plenum take-off examples is best? (illustration incl.)


  #1  
Old 01-26-07, 02:22 AM
S
Member
Thread Starter
Join Date: Jan 2007
Posts: 5
Upvotes: 0
Received 0 Upvotes on 0 Posts
Which of these 4 plenum take-off examples is best? (illustration incl.)

Goodman AEPF18301 Variable Speed Air Handler (w/GSH130301 13-seer 2.5ton Heat Pump)
1200 sqft single story home in Los Angeles
Mounted on a table/platform up in the Attic floor & Positioned horizontally
-----------

Hello friends. I'm trying to decide which of these 4 methods is best for the takeoff on my new air handler.

Please take a look at the mickey-mouse diagrams I drew (link below) and give me yur thoughts if you can.



http://www.rawlsenterprises.com/plenum-takeoff-examples.jpg



P.S.
The factory airway opening cut out at the top this air handler is 17-1/2" wide x 11" deep. What size plenum would you build for your take-off choice?
 
  #2  
Old 01-26-07, 04:56 AM
airman.1994's Avatar
Member
Join Date: Dec 2005
Location: VA
Posts: 5,491
Upvotes: 0
Received 8 Upvotes on 8 Posts
Id have an HVAC company do a duct layout for you after they did a heat load on the home.
 
  #3  
Old 01-26-07, 05:31 AM
R
Member
Join Date: Jul 2005
Location: MO
Posts: 195
Upvotes: 0
Received 0 Upvotes on 0 Posts
It would all depend on the required duct sizes and the space that is available for duct. As stated a heat load then a designed system for your house.

I always prefered as much trunk (to keep flow and pressure) equal.
 
  #4  
Old 01-26-07, 08:47 AM
Ed Imeduc's Avatar
Member
Join Date: Aug 2002
Location: Mountain Williams Missouri
Posts: 17,505
Upvotes: 0
Received 1 Upvote on 1 Post
Wink

Id say why all the Y's .Id do a trunk line and tap off that.
2.5 ton= 1000 cfm, for a good job you need about 175sq" off the unit.
 
  #5  
Old 01-26-07, 09:49 AM
S
Member
Thread Starter
Join Date: Jan 2007
Posts: 5
Upvotes: 0
Received 0 Upvotes on 0 Posts
Airman, I am having an HVAC company do the job/layout but it doesn't mean they know what they're doing. I refuse to "take their word for it", and because I can't go to his prior customers and inspect their houses to make sure he's doing the job right I must "trust" his judgement. However, I know there are many HACK shaddy tree HVAC companies out there who will just slap up some flex duck, run it any which-a-kinda-way and call it a day with their hand out holding a big fat bill. So, like any good and concerned homeowner should be, I do not want my installation to be a candidate for the "wall of shame" over at hvac-talk.com. Therefore I come to the internet to see what good people like you and Ed Imeduc has to say about what I am about to experience.

Because of Ed......I left the first installer who never did a load calc, manual J or manual D on my house. He just said "Oh, I know these houses and you'll need a 3.5ton." and was about to charge me an arm & leg. After Ed's reply on another question here, I began questioning him and he couldn't answer saying this and that was not neccessary. I said thanks but no thanks and moved on. Now I found a reputable company, but I'm sending him through the ringer as well.
 

Last edited by ShannonRawls; 01-26-07 at 10:40 AM.
  #6  
Old 01-26-07, 10:52 AM
S
Member
Thread Starter
Join Date: Jan 2007
Posts: 5
Upvotes: 0
Received 0 Upvotes on 0 Posts
ED,
I questioned all the Wye's too. But the installer says coming off the end of the plenum would be better for airflow CFM. He suggested option #3, but I think option #4 is best for static pressure without much loss in CFM.

I can't do a trunk line based on the design of my attic. What do you suggest I have him do?
 
  #7  
Old 01-26-07, 02:58 PM
airman.1994's Avatar
Member
Join Date: Dec 2005
Location: VA
Posts: 5,491
Upvotes: 0
Received 8 Upvotes on 8 Posts
You should never have a runoff off the end cap of the main duct! I to quested the pics. Ed said it wright make sure you have some main trunk before the takeoffs.
 
 

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