Results 1 to 13 of 13
  1. #1
    Join Date
    May 2017
    Posts
    102
    Post Likes

    Available static pressure

    Hey Guys i keep messing around with learning duct design.
    Im looking at a 4 ton unit with 14 drops. 10 supply 4 returns. Between the filters grills and heat strips i keep having a higher DPL than ESP.
    Not sure what to do.
    System im using for illustration. Will put out .1 to .7 esp and meet my required cfm range for the house like 1580 sq ft.
    What am i doing wrong or what to do?

    Thanks



    Sent from my LG-M257 using Tapatalk

  2. #2
    Join Date
    Jan 2004
    Location
    PA
    Posts
    76,246
    Post Likes
    Are you adding the PD of all of the filter grilles? If so, don't. You only use the PD of the longest run. Same with supply.
    Contractor locator map

    How-to-apply-for-Professional

    How many times must one fix something before it is fixed?

  3. Likes Cool_man liked this post
  4. #3
    Join Date
    May 2017
    Posts
    102
    Post Likes
    Thread Starter
    Quote Originally Posted by beenthere View Post
    Are you adding the PD of all of the filter grilles? If so, don't. You only use the PD of the longest run. Same with supply.
    Yes i was adding each grill and each filter. That will help using only one number. Also same for dampers? Or zone controls?

    Sent from my LG-M257 using Tapatalk

  5. #4
    Join Date
    May 2017
    Posts
    102
    Post Likes
    Thread Starter
    Quote Originally Posted by beenthere View Post
    Are you adding the PD of all of the filter grilles? If so, don't. You only use the PD of the longest run. Same with supply.
    Yes i was adding each grill and each filter. That will help using only one number. Also same for dampers? Or zone controls?

    If only what you stated was there. I Would have two grills and one filter to add?

    Sent from my LG-M257 using Tapatalk

  6. #5
    Join Date
    Jan 2004
    Location
    PA
    Posts
    76,246
    Post Likes
    Same for each supply register and zone damper.

    So 1 return grille, 1 supply register, 1 zone damper, 1 set of aux heaters, 1 air filter. Plus 1 balancing damper, if you are going to install them.
    Contractor locator map

    How-to-apply-for-Professional

    How many times must one fix something before it is fixed?

  7. #6
    Join Date
    May 2017
    Posts
    102
    Post Likes
    Thread Starter
    Quote Originally Posted by beenthere View Post
    Same for each supply register and zone damper.

    So 1 return grille, 1 supply register, 1 zone damper, 1 set of aux heaters, 1 air filter. Plus 1 balancing damper, if you are going to install them.
    Thank you very much

    Sent from my LG-M257 using Tapatalk

  8. #7
    Join Date
    May 2017
    Posts
    102
    Post Likes
    Thread Starter
    Quote Originally Posted by beenthere View Post
    Same for each supply register and zone damper.

    So 1 return grille, 1 supply register, 1 zone damper, 1 set of aux heaters, 1 air filter. Plus 1 balancing damper, if you are going to install them.
    Quick question for TEL. Total effective length. Do i do the same longest run for return and supply or every main and branch throughout the duct system?

    Sent from my LG-M257 using Tapatalk

  9. #8
    Join Date
    Jan 2004
    Location
    PA
    Posts
    76,246
    Post Likes
    The longest single return and single supply combined.
    Contractor locator map

    How-to-apply-for-Professional

    How many times must one fix something before it is fixed?

  10. #9
    Join Date
    May 2017
    Posts
    102
    Post Likes
    Thread Starter
    Quote Originally Posted by beenthere View Post
    The longest single return and single supply combined.
    Thank you

    Sent from my LG-M257 using Tapatalk

  11. #10
    Join Date
    Aug 2009
    Location
    Beatrice, NE
    Posts
    7,104
    Post Likes
    Just a quick add in. The longest physical run may not be the longest TEL run so you will need to look at all of them to make sure that you are using the longest TEL not actual length.

  12. #11
    Join Date
    Jan 2015
    Location
    San Diego, CA
    Posts
    303
    Post Likes
    Quote Originally Posted by BNME8EZ View Post
    Just a quick add in. The longest physical run may not be the longest TEL run so you will need to look at all of them to make sure that you are using the longest TEL not actual length.
    I was about to post the same thing - you beat me to it.

  13. #12
    Join Date
    Aug 2009
    Location
    Beatrice, NE
    Posts
    7,104
    Post Likes
    You mean I beat someone. Usually others beat me to a post.

  14. #13
    Join Date
    Jan 2015
    Location
    San Diego, CA
    Posts
    303
    Post Likes
    Quote Originally Posted by BNME8EZ View Post
    You mean I beat someone. Usually others beat me to a post.
    LOL. I was going to "like" your last post but the like feature is not working for me.

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  

Related Forums

Plumbing Talks | Contractor MagazineThe place where Electrical professionals meet.