Roof Drain Pipe Connector Sizing

[JKRevit]

I’m trying to build some intelligence into a pipe connector for a roof drain family. I would like a parameter for Roof Area to control the Pipe Diameter parameter. I don’t know how to write a statement that defines a range of values, (Roof Area in this case), to assign to each Pipe Diameter.

In broad terms, I need to create a statement that says, “If the Roof Area parameter is less than this value (Roof Area), but greater than this value, (Roof Area), assign this Pipe Diameter”. I have made a Shared Parameter for Roof Area. Would a conditional, if/than statement be better for this family, or do I need to build a Lookup Table? Any suggestions would be welcome.

[nathan.chapman]

It would look something like this. Just remember that the < does not include equal so you will have to go a value over the max or value under for min. So another way to write it would be if(and(not(....>250... That would mean equal to or less than 250.
Boolean.PNG
Boolean expression would be your best option as lookup tables do not work with ranges. They are looking for an exact match. Now you could have the Boolean define a value that is looked up in the lookup table.

[JKRevit]

Nathan;
Thanks for your quick reply. I looked at your attachment, and I think I understand how it functions. What purpose does the 1/4" serve near the end of the statement? I'm trying to learn how to write conditional statements. Can you recommend any resource to learn more about them, and how to build them?

[nathan.chapman]

JKRevit
The 1/4" at the end is what will be shown if nothing is found to be true in the equation. Its what is called the "if not" value. If everything is not true then give me the 1/4". I would make the value a crazy number so it will stand out if a odd value is entered into the roof area.
As far as resources I really don't know of any off the top of my head. I remember having a class on them back in engineering school but i learned most by trial and error building Revit families over the years. Don't hesitate to ask questions here if your stuck.

[JKRevit]

Thanks Nathan!!

I've completed my Boolean statement, and my pipe diameter parameter is changing in proportion to the Roof Area parameter. This is good news. This will work well for tagging a Roof Drain family built with these parameters. Because the Roof Area quantity will vary with each Roof Drain, I made the Roof Area parameter an Instance parameter. A Type Parameter won't serve my need in this case. I originally hoped to constrain the Pipe Diameter parameter with the Roof Area parameter. However, an error message tells me: Instance Parameters can't be used in Type Parameter formulas. The Diameter and Radius parameters for Pipe Connectors are always Type Parameters. Can you suggest a way to get around the Type/Instance conflict that would allow me to control the Pipe Diameter parameter with the Roof Area parameter?

[nathan.chapman]

The only way that you could get around this is to create your own parameter that would control the dfu/sfu on the connectors. I'm not sure if you schedule these but if you do then make sure its a shared parameter.