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  1. #1
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    Sampling static pressure

    Does anyone have a good diagram or easy explaination on where to take static pressure readings on an RTU? The question is geared toward the return side....is your TSP referencing before or after the draw through coil?

    BDP 588ANW060100

    http://www.docs.hvacpartners.com/idc...i588a-18-9.pdf
    http://www.docs.hvacpartners.com/idc...588a.18.4b.pdf

  2. #2
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    The blower performance chart is using External Static Pressure (see pg. 41 of your first link).

    I would punch wholes in the duct next to the unit if it's a horizontal discharge.

    If it's vertical discharge, I'd punch wholes in the horizontal duct connection panels.

    If you wanted to use the wet coil pressure drop table on page 44, you'd punch holes in the blower access door and the return panel/duct.
    Perhaps you should have read the instructions before calling.

  3. #3
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    Total Static Pressure is fan discharge static-fan suction static.

    External Static Pressure is supply static-return static

    If the fan discharge static is 2" w.c and the fan suction static is -1", the fan's TSP would be 3" (2"-(-1")


  4. #4
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    thanks!

  5. #5
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    Quote Originally Posted by BergerMech Rob View Post
    Total Static Pressure is fan discharge static-fan suction static.

    External Static Pressure is supply static-return static

    If the fan discharge static is 2" w.c and the fan suction static is -1", the fan's TSP would be 3" (2"-(-1")

    this diagram is one of the best explanations that i have ever seen!

    thanks!
    When I am late for work, I usually make up for it by leaving early.

  6. #6
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    Glad I could be of assistance.

  7. #7
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    Quote Originally Posted by BergerMech Rob View Post
    Total Static Pressure is fan discharge static-fan suction static.

    External Static Pressure is supply static-return static

    If the fan discharge static is 2" w.c and the fan suction static is -1", the fan's TSP would be 3" (2"-(-1")

    thanks.

  8. #8
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    thanks for the diagram
    If you help others then you are a Success

  9. #9
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    Static Pressure (Sp) This is pressure that is exerted in all directions of a duct. When static pressure = total pressure there would be no flow.

    Velocity Pressure (Vp) The difference between total pressure and static pressure.

    Total Pressure = Static Pressure + Velocity Pressure.

  10. #10
    Join Date
    Jul 2009
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    Good diagram can somone also diagram this for an AHU with a SF and a RF

  11. #11
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    I modified it a bit to show a little more detail and now it has a supply and return fan.
    Last edited by Tech Rob; 02-08-2010 at 08:46 PM.

  12. #12
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    Jul 2009
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    Ext SP

    Thanks for the new diagram with the SF and RF. Thats about what I figured. But the reason I wasn't sure is becuase on the Fan shcedule ( on the plans) it has a design ESP for each fan. ( SF & RF ) while I would expect to see a design TP for each fan I thought I would only see one ESP for the AHU not the way they have it...so i'm still a lil confused...but thank you for confirming what I thought...Noel

  13. #13
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    Mar 2007
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    Quote Originally Posted by Noelcon View Post
    Thanks for the new diagram with the SF and RF. Thats about what I figured. But the reason I wasn't sure is becuase on the Fan shcedule ( on the plans) it has a design ESP for each fan. ( SF & RF ) while I would expect to see a design TP for each fan I thought I would only see one ESP for the AHU not the way they have it...so i'm still a lil confused...but thank you for confirming what I thought...Noel
    I don't see how you could have more than one ESP for the same piece of equipment. I'd put in a request for information to that engineer, and maybe he can put a good word in for you with his dealer
    Last edited by Tech Rob; 02-09-2010 at 07:31 PM.

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