Page 1 of 2 12 LastLast
Results 1 to 10 of 11

Thread: hi..dears pls solve my problem..i need the total flow here..

  1. #1
    Member
    Join Date
    2009-11
    Posts
    2
    Login to Give a bone
    0

    Question hi..dears pls solve my problem..i need the total flow here..

    hi dearsss...i need the total flow..at the end of the duct..before and after vav..wht paramerers i should change???can anyone explane the steps..?..i changed "i changed calculated and preset also..still m nt getting the flow..... i attatched my file..
    Attached Files Attached Files

  2. #2
    All AUGI, all the time JoelLondenberg's Avatar
    Join Date
    2015-10
    Posts
    508
    Login to Give a bone
    0

    Default Re: hi..dears pls solve my problem..i need the total flow here..

    The only problem you are having is that you are driving the flow in the VAV box in two different ways. You have a parameter for air flow linked to both connectors, but you also have the connectors linked.

    The way this is intended to work is to have the down stream connector set to "Calculated" in order to collect data from the air terminals, then link this to the air flow parameter. The upstream connector should be set to "Preset" and linked to the same air flow parameter. This collects data from the parameter and pushes it in to the upstream duct.

    If you use any combination of the air flow parameter AND linking connector to connector, then Revit apparently cannot figure out which one should be driving.

    Also, as you are laying out your system, it is better not to cap the end. When you are sorting out flow issues, Revit will need to have exactly one path for flow. An open end is considered a possible path. If you have an unfinished branch and want to exclude that from the flow calc's, cap that but leave one end open. This applies to both pipe and duct.
    Attached Images Attached Images
    Last edited by jlondenberg; 2010-03-21 at 05:48 PM.

  3. #3
    Member
    Join Date
    2009-11
    Posts
    2
    Login to Give a bone
    0

    Default Re: hi..dears pls solve my problem..i need the total flow here..

    hi...thanks mr..jlondenberg..its working.. thank u so much....and.if it s is like that wht is the advantage of linking the connectors???
    Last edited by babugd; 2010-03-21 at 07:56 PM. Reason: need to clarify more..

  4. #4
    All AUGI, all the time JoelLondenberg's Avatar
    Join Date
    2015-10
    Posts
    508
    Login to Give a bone
    0

    Default Re: hi..dears pls solve my problem..i need the total flow here..

    Linking connectors is for families like fittings where you won't be using a parameter to capture the flow value.

  5. #5
    I could stop if I wanted to
    Join Date
    2015-09
    Posts
    481
    Login to Give a bone
    0

    Default Re: hi..dears pls solve my problem..i need the total flow here..

    I am having a similar issue, but i have checked the linking and the preset/calc parameters and mine look fine.

    The flow data will not show for the duct upstream of the box. I have attached the family if anyone wants to take a look.
    Attached Files Attached Files

  6. #6
    100 Club jbaumann's Avatar
    Join Date
    2006-08
    Location
    Riverside, CA
    Posts
    109
    Login to Give a bone
    0

    Default Re: hi..dears pls solve my problem..i need the total flow here..

    Quote Originally Posted by kgrant.115222 View Post
    I am having a similar issue, but i have checked the linking and the preset/calc parameters and mine look fine.

    The flow data will not show for the duct upstream of the box. I have attached the family if anyone wants to take a look.
    You have two upstream connectors as shown in the image. My assumption is that you want the total of both these connectors to equal the downstream "Supply Air Flow". How is Revit going to determine how much air goes to each?

    You will have to manually enter the ratio or flow of one of the upstream connectors and formula the other to equal "Supply Air Flow-Manually entered parameter"

    If both upstream should simply equal the total of the downstream "Supply Air Flow" then simply set them =Supply Air Flow in the formula field.

  7. #7
    I could stop if I wanted to
    Join Date
    2015-09
    Posts
    481
    Login to Give a bone
    0

    Default Re: hi..dears pls solve my problem..i need the total flow here..

    Thank you for the response. I forgot to reply to this when i figured it out yesterday. I'm not sure how i overlooked the 'supply air' flow parameter in this.

    Thanks again though

  8. #8
    Active Member
    Join Date
    2009-07
    Location
    Seattle, WA
    Posts
    73
    Login to Give a bone
    0

    Default Re: hi..dears pls solve my problem..i need the total flow here..

    This is not technically a reply to the original question but I've been having a similar problem with flow calculations, especially across fittings. In some cases I'll have the flow disappear after an elbow, tee, or tap. In others, the flow will carry across elbows but disappear at the tap. In all these cases the diffusers downstream had a CFM assigned to them. (I've also had similar problems with pipes/plumbing)

    So as I was trying to find out what was different between the elbows that dropped the flow data and the elbows that carried the flow data, I found that the elbows that didn't work had a blank in the ASHRAE slot. The elbows that worked had something in it, in this case it was CD3-11. So I tried entering that into the elbow that didn't work and I couldn't, it wouldn't let me type anything, the drop down menu showed nothing. It seems that it has to be linked to something. (see attached images). So I started checking fittings that didn't work and none of the them had input in the ASHRAE Table slot.

    The annoying things are, first, that it's not working, and second, that it's inconsistant. In both cases, the fittings are the same (default ootb) and were placed the same way. . . I simply ran ductwork and Revit placed the fittings where needed.

    Any ideas?

    Dave
    Attached Images Attached Images

  9. #9
    I could stop if I wanted to
    Join Date
    2015-09
    Posts
    481
    Login to Give a bone
    0

    Default Re: hi..dears pls solve my problem..i need the total flow here..

    Have you tried deleting the fitting and redrawing it? I know you shouldn't have to, but there are several times when things are not working out for me that if i delete something and remake it works out fine.

  10. #10
    I could stop if I wanted to
    Join Date
    2007-06
    Location
    Des Moines, IA
    Posts
    224
    Login to Give a bone
    0

    Default Re: hi..dears pls solve my problem..i need the total flow here..

    I've had this issue with piping and flow not propagating through fittings. I haven't had it with ductwork (yet) but the thing with the ASHRAE table is just a coincidence, or should I say byproduct of the flow not propagating. Something else is causing the issue, not that it can't find a lookup table. Redrawing is the only thing that helped me with the piping fitting problem.

Page 1 of 2 12 LastLast

Similar Threads

  1. 2015: Flow Calculation problem
    By yves.n544759 in forum Revit MEP - Families
    Replies: 2
    Last Post: 2014-12-11, 07:28 AM
  2. Piping System Flow Problem
    By WT-09 in forum Revit MEP - General
    Replies: 6
    Last Post: 2011-12-19, 08:58 AM
  3. Wye Combination w/8th Blend flow direction problem
    By jamstearns in forum Revit MEP - General
    Replies: 8
    Last Post: 2011-02-28, 01:50 PM
  4. Help! Total Newbie - Uvw problem
    By Grumple in forum 3ds Max - General
    Replies: 3
    Last Post: 2008-10-28, 02:34 PM
  5. It is time for another problem to solve
    By Noahma2 in forum AutoCAD General
    Replies: 9
    Last Post: 2007-07-11, 12:55 AM

Posting Permissions

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