ProjX RTU Ductwork Modeling

Okay. In this video, I'm going to be doing the air distribution coming off of this RTU unit. So basically what we want is we want return air duct come down and stub out, and then we're going to have supply air duct coming off the sides here and distributing duct with duct mounted air diffusers. So we can get started. I'm gonna select the rooftop unit.

I'm gonna right click here, draw a duct, and if I just start drawing duct and click, it's not gonna let me do it because I haven't given it enough space. So what I like to do when coming off of rooftop equipment like this, is I tell it to go down way further than I know it needs to be, just to give myself enough space. I'm gonna type in like 10 feet off the deck, and place my duct, and then that will give me plenty of space to make those fitting. So if I go to that vertical section there, I can see that the duct is you know, ridiculously way down here, but it made the fitting and it's quite easy to just then come in and adjust the size. And then I'm to change that to something easy to type in like that.

Alright. So there we go. And so I've got my return error. Let's come back to my new work. And I'm going to put a diffuser on that.

Okay. Now let's deal with the supply air. So what I want is I want a straight bit of rectangular duct to come straight down and then cap itself, and then I wanna tap off round duct to come out like this. It's a very simple system. So what I'm gonna do is I'm gonna select the unit, right click, draw duct, and I'm say middle elevation, and I'm say something like 15 feet, and it's still in duct draw mode, but I don't want to branch off, I'm not trying to go horizontal here, I just want that straight bit of duct, so now I hit apply, and it creates that bit of duct.

So if we check out the section, there we go. And it it made it a lot longer than I wanted it to. So let me change that bottom elevation to I think 17 feet one. Yeah. Let's go 16. Let's go a little bit lower actually. Let's go sixteen six. Alright. And then I'm gonna cap that open end. Okay.

I'll come back to new work. Okay. And then I want to do round duct that connects into that duct. So I'm gonna start drawing, so DT, and change the duct type to round straight tap and I'm gonna change the diameter to something more reasonable like 16 inches and then at the middle elevation, I'm gonna make I'm gonna make that be 18 inches for now, I can adjust that if I need to. Alright.

And then I'm gonna start drawing and want that to be tap into that. It's a little off center, so I'm going to use the align tool to align that nicely. And then gonna check it out here. Yeah, I like that. So then I go back into floor plan, create similar, start drawing from that bit of duct and go like this.

Line those two and I'm gonna cap open end, cap open end. Okay. And now I want to get my on duct diffusers set, so I'm gonna come over to my air terminals in the warehouse. I have a duct mounted diffuser family that I like, so I'm gonna copy that, come back over here, paste it into the space, so now I have it to work with. I'm gonna select this and I'm gonna say create similar, and Revit can be a little fussy about getting the air terminals actually on the duct.

So you need to get air terminal on duct button highlighted, so click make sure if it's not clicked, make sure it's clicked. And then k. And see that turned blue. It adopted the settings. If it if I hadn't gotten it on the duct, it would still be black like this one. I'll show you a little easier in thick line. Alright. So I'm gonna delete that and then I'm gonna create more. Let's see that one didn't make it even though as far as I can tell I did exactly the same thing. I'm gonna hit CS again, and yeah that one got in there.

I haven't quite figured out why Revit's so fussy about that one. Alright. Let's do the other side. And here. Here.

Alright. Alright. Those are all on there. And then I'm gonna use the split element tool to split the duct like so. And then I'm gonna select all instances of this duct visible in view. So I've got those all selected. I'm gonna say the CFM for each of these is I wanna go two fifty. Obviously you would actually be entering values in off of a loads calc. I'm just you know, guesstimating somewhat ballpark numbers, so we have something to work with. Alright.

So we have those in there. Now I'm going to size this duct system and something to note about these diffusers, the next size is an instance parameter. And if if the next size is and and the whole size of the family is based off the next size. So basically it's an instance family. What that means if you size the duct, when you size duct, it will resize the next size of the connector in the family if the parameter is instanced and it won't if it's type.

So let me demonstrate what I mean by that. So I'm just going to size this bit of duct here, I'm gonna say duct pipe sizing, and I say okay, do the thing. And it's making a liar out of me because it didn't change those, which is oh, that's because I had just the just the bit of duct selected. If I've got the air terminal selected as well and hit duct pipe sizing, say okay, it's gonna resize those for me, which isn't what I wanted. So I'm gonna control z that.

So that's just something to keep in mind, if you don't want Revit to resize the neck connection of your air terminals that are instance based, when you select a whole duct system like this to size it, go ahead and do that, but then go into filter and deselect air terminals, and then do the duct pipe sizing, and it'll size the duct for you, but it won't resize the air terminals for you. So this actually happened over here with these diffusers. So these diffusers, the connection diameter is an instance parameter, and when we size it, it's sized the neck based on the connection. So I'm just gonna demonstrate. So if I manually change this to say 16 inches Oh, that's just making it a little too big.

Let's do it with Well, what I'm gonna do is I'm just gonna drop these down, give ourselves some room. Put those down to six feet off the deck, we'll have plenty of space and I'm gonna go into a three d view so you can see what we're doing here. So on these two, if I change the connection diameter to 16 inches, there we go, got a 16 inch connection diameter. And this one I'm gonna change just so we can see what's going on here. I'm gonna change the diameter of the ducts to 16 inches as well.

Alright. So there we go. So these are oversized ducts at the moment. So if I select if I select this branch and I've also got the air terminal selected and I say duct pipe sizing, go ahead go ahead and do it. It's gonna resize the the neck, which is actually nice if that's what you want.

It's quite handy that Revit does that for you, but in some instances that might not be what you want. So in that case, if I wanted to keep the 16 inch neck size, what I would do is I would I would select that branch, and then I would deselect the air terminal, and I would say duct pipe sizing. Okay. And it'll keep that 16 inch connection, but then resize the duct. So that's just something to keep in mind how that works. And then you will be empowered to have Revit do exactly what you want. In this case, I like I like the smaller neck size, so I'm going to do that. Dual sizing. Okay. Move this back up to eight feet.

Alright. That was a little air terminal side quest lesson there. So we've got our duck sized here. Let's look at this. We've got 3,500 CFM. We've got our air terminals sized the way we want. And let's get this size, so this is actually 3,500 CFM. Let's see what we've got coming in here. So point o four, you know, I'm actually I'm gonna say I'm fine with that size. I'm not gonna ask it to auto size.

I'll just take what's coming out of the RTU. Again, we could we could demonstrate what I just said with the air terminal. So if we selected this, I'll just show this so you can get another sense of it. And then I size it. Okay. You see it resized that air terminal, which maybe that's what I want, maybe that's not what I want, but that's what it did. So if I control z that and then select that again and I deselect the air terminal and I say duct pipe sizing. It won't change. It won't change the size of it. So control z because I actually like the sizing just the way it is.

Okay. So that concludes the modeling for the airside distribution for the RTU.