Results 1 to 9 of 9

Thread: Building Pressure Relief Duct Sizing

  1. #1
    Join Date
    May 2009
    Location
    South of Heaven
    Posts
    1,406
    Post Likes

    Building Pressure Relief Duct Sizing

    Fellow Field Engineers ,

    I hope it's ok to ask this question here , I figured a TAB technician would have the most experience with this.

    I am being asked to size a barometric relief opening for a building with a very large AHU ( indoor pool facility ). I am guessing that I will use ...

    - maximum building static ( vs outdoor )
    - maximum cfm of the supply fan
    - a ? velocity

    What would be the maximum velocity I could safely get by with ? I'm just rolling the dice and going with 1000 fpm but I really have no idea. Any thoughts are appreciated.

  2. #2
    Join Date
    Aug 2002
    Location
    Southold, NY
    Posts
    30,041
    Post Likes
    My 1st question is WHY a Pressure relief?

    that room should have a significant outside air system with an exhaust to match.

  3. #3
    Join Date
    May 2009
    Location
    South of Heaven
    Posts
    1,406
    Post Likes
    Thread Starter
    There have been 2 events that involved an exhaust fan failure. An electronic interlock will also be installed but they are also asking for the mechanical relief.

  4. #4
    Join Date
    Feb 2016
    Location
    Louisburg Kansas
    Posts
    4,886
    Post Likes
    They need powered exhaust especially if they have adjoining areas where high humidity can cause problems. They should be using an air handler designed for conditioning swimming pool enclosures.
    Not trying to avoid your question but if it doesn't work and probably won't they will blame you and if they have water damage they will probably want you to pay to fix it.
    No man can be both ignorant and free.
    Thomas Jefferson

  5. #5
    Join Date
    Aug 2002
    Location
    Southold, NY
    Posts
    30,041
    Post Likes
    What make and model of equipment is in this Pool Room?

  6. #6
    Join Date
    Feb 2004
    Location
    New Mexico
    Posts
    9,841
    Post Likes
    Is the pool equipment 100% outside air type or a water re-cycle heat pump system?
    Give me a relay with big enough contacts, and I'll run the world!

    You can be anything you want......As long as you don't suck at it.

    If a person wants to create a machine that will be more likely to fail...Make it complicated.

    USAF 98 Bomb Wing 1960-66 SMW Lu49

  7. #7
    Join Date
    Oct 2016
    Posts
    1,977
    Post Likes
    Quote Originally Posted by tech45 View Post
    There have been 2 events that involved an exhaust fan failure. An electronic interlock will also be installed but they are also asking for the mechanical relief.
    Maybe you could talk them into a back-up exhaust fan. I would think sizing for 1000 fpm would be okay. You would want to look at how much pressure loss the hood or louver would have at your total flow. That would pretty much be what the building pressure would be with no other influences. No insect screen...

  8. #8
    Join Date
    May 2009
    Location
    South of Heaven
    Posts
    1,406
    Post Likes
    Thread Starter
    100 percent OA.

    Innovent , 20 plus hp motors. I don't have a specific model number at this moment. And I'm not clear on why the exhaust fan failure did not stop the unit , I have not dug into this job yet. Innovent has good documentation and support from my experience so I'm just not real concerned about the machine at this point in time.

    But I can tell you that I will be sizing a mechanical relief duct / damper per the direction of the building owner ( regardless of anything else that is discovered ). Apparently the over - pressure issues caused damage to some roofing or something .

  9. #9
    Join Date
    Mar 2015
    Location
    Medford, N.Y.
    Posts
    7,286
    Post Likes
    Add this to the mix, the room air temp is supposed to be 2*F warmer than the water temp. So air exchange is critical.

Posting Permissions

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