Who's Your Daddy? Logical Relationships in Revit MEP

This is an echo of a post from October 2011. I emphasize this concept in every session I do that is focused on Revit MEP and I think it's worth stating again.

Revit MEP elements, like electrical panels and receptacles or HVAC equipment and diffusers, have a Parent - Child relationship. Revit calls this a Logical Relationship. In contrast the physical relationship is described with duct/pipe but there is no equal for electrical systems. It could be with conduit or cable tray but no such relationship exists yet.

The other day we were chatting about this in class and I blurted out "You know, like who's your Daddy?" I was kidding but one of the guys said that it will actually help him remember to start with the "child" part of the relationship. For example, you start with a receptacle and create a power circuit (system), then choose the Daddy, the electrical panel it gets power from. This relationship continues up through the grandparents, great grandparents etc. When everything is assigned correctly you can see this family tree in the System Browser.

So if it helps, when you are creating relationships between elements with Revit MEP, just remember "Who's your Daddy"! START with the child and then assign the Daddy.

Revit Systems and Daycare

You probably wouldn't put those two in the same sentence? Imagine a daycare center with a hundred children running around and no supervision. Now imagine the same thing but put ten adult teachers in the room. It is probably not nearly as chaotic as the first situation.

Now change the center to Revit and the children to MEP component families. Without assigned systems it is much like that unsupervised daycare center. Each system functions like a teacher or parent assigned to several specific children to keep things organized. Ultimately this allows Revit to function more efficiently.

Isn't it interesting how effective the use of family and people concepts extend to Revit ideas and features.

Set Calculations to Stun

Attending sessions at a conference is always a good way to come up with ideas for new blog posts. This post was inspired by David Butt's session at Autodesk University 2012 about Pipe and Duct Systems. I was working as one of his lab assistants and he mentioned this so I made a note to myself to mention it again, here.

By the way sorry about the title, I was thinking of the Star Trek "Set phasers to Stun" command that Captain Kirk often uttered. Literary license, I was just rhyming Stun with None.

In Revit MEP you can create systems for pipe and duct, meaning just the act of sketching one of them assigned to a particular system will impose certain design properties and graphical qualities to that element automatically. In the past the only way a duct or pipe could behave this way was to connect it to a component or to another duct or pipe that was already. That made it harder to just sketch pipe or duct (schematic design) and use it to represent different uses, like supply or return air, or hot versus cold water.

One of the properties of these systems is called Calculations and you can choose between None, Flow Only or All.

Since Revit only does fluid based calculations (piping) it doesn't make much sense to "waste" any CPU cycles on trying to do calculations on pipe systems for gases like oxygen or nitrogen. Same is true if you really aren't going to rely on Revit for pipe sizing or related calculations either. Any system that isn't going to need this ought to be assigned to None.

Who's Your Daddy - Revit MEP Relationships

Revit MEP elements like electrical panels and receptacles or HVAC equipment and diffusers have a Parent - Child relationship. The other day we were chatting about this in class and I blurted out "You know, like whose your Daddy?" I was kidding but one of the guys said that it actually helps remember to start with the "child" part of the relationship. For example, you start with a receptacle and create a power circuit, then choose the "Daddy", the electrical panel it gets power from. This relationship continues up through the grandparents, great grandparents etc. When everything is assigned correctly you can "see" this "family tree" in the System Browser.

So if it helps, when you are creating relationships between elements with Revit MEP, just remember "Whose your Daddy"! Start with the child and then assign the Daddy...

Dept. of Duh - Deleting a System the Easy Way

Okay I'm not the sharpest tack at times. Using Revit MEP, I was asked how best to delete a system, like a circuit or supply air system. I started to suggest it was easy using the System Browser. One of the students then said, "Why don't you just use the delete key?". Uh...well that works too! It isn't obvious, at least it wasn't to me, but you can select your system and hit the DELETE key, gone it is! You can also activate the Modify Ribbon to click on the Delete button (Red X). It's pretty effective eh?? Here's a VIDEO just in case this text is mumbo jumbo.