No Loss Defined

[revitworkbench]

Hi I am getting related warnings on my systems that says I have "No loss defined" in my fittings. How do I define loss so that Revit understands and my systems pressure loss is accurate? I thought Revit had a look up table for this sort of thing. Thanks!

[CoreyDaun]

I *think* that your System has to be "Properly Connected" first, and then the "Loss Method Settings" list (as depicted in the image below) will populate. Also, search this forum as there may be more information to this issue.

[abulla]

We've been ignoring "No loss defined" warnings, just because it's so quirky, and it doesn't seem to affect the actual duct flows. I did some experimenting with an older project this morning and I couldn't get rid of all the errors.

[CoreyDaun]

I'll buy that. I drew up a very simple system, and as long as it was all connected, there were no warnings - except when a union was placed, which caused the "No Loss Defined" error in my test System. ~shrugs~

[revitworkbench]

I see the "Coefficient from ASHRAE Table" selection and the "Loss Method Settings" Edit button. But the edit button brings up another dropdown menu that is blank. Shouldnt there be choices in here? If so, how do I load them? If not, are these ASHRAE Tables up-to-date? How do you tell whats going on inside the black box? How does Revit know what ASHRAE table is correct? I mean you can change a fitting just too many ways, can a table matrix really keep up with that?

[CoreyDaun]

---

michaelmead wrote:
"I see the "Coefficient from ASHRAE Table" selection and the "Loss Method Settings" Edit button. But the edit button brings up another dropdown menu that is blank. Shouldnt there be choices in here? If so, how do I load them? If not, are these ASHRAE Tables up-to-date? How do you tell whats going on inside the black box? How does Revit know what ASHRAE table is correct? I mean you can change a fitting just too many ways, can a table matrix really keep up with that?"

---

This is getting beyond my knowledge. As I said in my first reply - your system has to be "Well Connected" and then that pull-down list will allow you to select the ASHRAE table for the select Fittings. Try creating a simple duct system in a new project and experiment. There was a recent post in which someone mentioned that it automatically chose the first table on the list.

[revitworkbench]

Im not sure I know what you mean by "well connected" but I do have everything connected and working properly, except for this. But Even in th picture that you posted, your edit-dropdown menu is empty. Is yours a simple, well-connected system? If so then why is your table dropdown menu blank?

[revitworkbench · Accepted solution]

Duct Fitting Table Viewer is available on the exchange website. Its Free, it works, and it solves my issues 🙂