Set loss method settings for ducts pressure drop via node

I’m trying to set the following two Built-in parameters via Dynamo for duct pressure loss calculations:
Pressure Loss Method → Set to specific coefficient
Loss Method Settings → Set a specific K coefficient given as input for each duct fitting

I’ve tried some nodes, recently the Set BuiltIn Parameter from Archi-lab but it gives me an error in the code.

I’ve also found in the API repository that they should be named: “RBS_DUCT_FITTING_LOSS_METHOD_SETTINGS” & “RBS_DUCT_FITTING_LOSS_METHOD_SERVER_PARAM”

Have somebody tried access & modify these 2 parameter?

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Hi @gianluca.pilati1 is it something here you are after…seems controlled by a guid

Gs8BQS10Kz

Yes exactly for the “Loss Method” parameter, same I’d like to do for the “Loss Method Settings”, passing a value (double) as Specific Coefficient for each fitting.

Where did you get these GUIds from?
Thanks!

something here ? you can the guid just with get parameter…

Revit_ndklFx4XVE

take a look on this one here…Change Duct Loss Coefficient to Another Fitting in ASHRAE Table - #6 by junny

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Yes exactly like this. Could you share that piece of code?
I’ve tried to adapt the til.shviger code a while ago but was having issues with Revit 2024.

yeah sure but first tomorrow, im not at pc before that

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try as here should run with ironpython 2 or ironpython 3


loss methods.dyn (28.0 KB)

Thanks now it works!
I still have a problem on the first run on new fittings when no values were set for the Specific Coefficient.
Found out that when the field is empty the script doesn’t run.


Also I’m thinking a way to re-run the Revit pressure drop overall calc after the modification, since as described in other posts, it won’t automatically update.

allrihgt not sure i cant do that…seems work fine here…i think…probably i misunderstand, becoarse my duct fitting always have a value with startup…0.0 in settings—specific coefficient and not empty

Yes I think it happens when you have a fitting already connected to a duct system

i guess i have…hmmm here i just open a new clean project, so my schema is clean and still 0.0 in value

It might be a glitch of Revit systems that cause it? Would it be possible to add an “if” in the code to deal with this without breaking the run?

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yeah probably, try it :wink: but sounds more as a transaction thing for me maybe…

arhhh noew i see it when open a ootb mechanical template…then its empty, true…i will take a look on that situation. here in the weekend…and see if it could be fixed…

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