Calling all duct layout experts!!

[vaughndave]

I am attaching two families for experimentation.
I don't know what I am doing wrong but When creating a simple supply system using these two families I cannot get the branch between the AHU and the VAV box to size correctly.
In most cases I get this error:
Sizing failed. Flow for section is 0.
Please help!!

[Victor.Ramsey]

Looks like the problem I'm having with those components is with the Trane AHU you've attached, I don't know how it was created but it is wrong. If you replace your duct connectors and edit their size under their element properties it should work for you. Before you delete the old ones go into your respective views and extrude a shape the size and location of the current and then you will be able to place them on the face of the extrusion in the exact location required. I’m not sure how the ones that are placed that are there because some have no face to attach to and the sizes are grayed out in their properties dialogue box. Hope that helps.

[vaughndave]

Victor,
Thanks for your reply, however, the connectors are fine as far as how they were put on the geometry. I just used pick a working plane and attached them in that manner rather than face. The sizes are grayed out because if you look to the right of each size readout there is an equals box....I assigned a parameter to each so that I could customize the instance parameter of each of the connectors.
I need more help!! Anyone?

[tys90]

I am attaching two families for experimentation.
I don't know what I am doing wrong but When creating a simple supply system using these two families I cannot get the branch between the AHU and the VAV box to size correctly.
In most cases I get this error:
Sizing failed. Flow for section is 0.
Please help!!

Your connector on the VAV box inlet is wrong, take a look at the PDF I uploaded. Then link your connector CFM to your primary air flow parameter.

[vaughndave]

Here are new Family items attached. Things still are not working. I looked at the pdf's and links to shed some light....I just don't know where to start here. This is quite complicated since there really isn't any solid info on how to build these items. I don't know any more what parameters I have right and which ones I don't.
HELP PLEASE!!

[tys90]

Here are new Family items attached. Things still are not working. I looked at the pdf's and links to shed some light....I just don't know where to start here. This is quite complicated since there really isn't any solid info on how to build these items. I don't know any more what parameters I have right and which ones I don't.
HELP PLEASE!!

Sorry about that, the PDF covers a little bit more than your exact problem you are having. I'll explain some more. I downloaded your original families, changed the Inlet (primary) air connector to "preset" and then linked the value to your primary airflow parameter. Then I loaded the families into a blank project, connected the supply of the AHU to the inlet of the VAV box then specified a primary airflow of 500 CFM in the element properties of the VAV box. This allowed me to size the ductwork from the AHU to the vav box and gave me pressure drops and enabled the duct inspector.

That said, for correct propagation of airflow through a system, from diffusers through VAVs to the AHUs, the PDF will cover what each connector on each device needs to be set at.

[vaughndave]

Please take a look at this VAV box.
Why does the element properties of the VAV box, not show any values for airflow for the “Other air” Connector when connected in a simple system?
Also, When is a link necessary to use if at all and why?

Thanks,
Dave

[kyle.bernhardt]

Dave,
Check out the posts I made on Inside the System a while back, should explain how flow propagates through systems.

Post 1
Post 2

Cheers,
Kyle B