Autosizing Ductwork

K. In this video, I'm going to show how to use duct sizing, to rapidly size duct. So, I've got a 3rd Floor space here. I've got an RT unit on the roof above it, and I'm going to do a quick and simple layout. So I'm gonna hit a t to enter, air terminals. I'm going to select a fives. That's fine, for the purposes of this video. And then I'm going to look at the elevation from level default to set eight, which is where my ceiling is at. So I'm good with the elevation. I know I'm not putting these on the floor.

I'm happy with that. Now I'm gonna put the main duct in, so I'm gonna hit d t to enter duct drawing mode. And I want rectangular for this. And for this, I'm actually gonna choose mitered, a rectangle mitered with taps, and then I'm gonna mouse over until I get this blue dotted line to show that it's lining up with that RTU connector. Gonna click once there. To set it, my middle elevation is nine. That's probably a little low, but I'm gonna go with it for now. I get that in there. You know, I've intentionally made this a sort of ridiculously small duct. That's fine.

And I'm going to cap that open end. So this is what we're working with here. And the reason I drew this in so so low is so that it would give me give this space to generate the transitions that it needed. I'm gonna change this to a 60 degree. So it gave me space to make the transitions without breaking this. So now I am going to bump it up. 10.5 should probably do. Okay. So I've got that, and then I'm going to I'm gonna select this. This is just a little tip.

I'm gonna select this main. I'm gonna say CS for create similar. So that's creating a duct that's at the exact same elevation. I'm gonna change my type to round straight tap balancing damper. And I'm gonna give put my branch ducts in here. You notice I'm not paying very much attention to the size of these. That's because I'm gonna have Revit do the work for me. And go like that. And then a flex duct, FD for flex duct. I just need to make sure that the system type is supplier because I'm doing supplier type here and make these connections.

Now you know, so I'm in a working view. So when I tag this, I'm just tagging this as part of my own design flow. This has nothing to do with with sheets with sheet presentation. So I can come in here and edit this tag. That's the flow. So I'm gonna say 350. That's 350 CFM. This air terminal now knows that it's pushing pushing out 350 CFM. So I'm just going to select the other ones, and the other place to enter CFM information, of course, is here. So I'm gonna enter that in there.

And now if I select these branch ducts, you'll notice that they know they've got 350 CFM running through them. They all do. And so does this main. It knows that it's got 1,400 CFM going through it. Now I'd like to size this, but I know that I would like this bit of the main to be a different size than this bit of the main. So I'm gonna use the slice tool, that's SL, and give a little slice right there. So now this piece of duct has 700 CFM, and this one has 1,400 CFM. Okay. So that's good. I'm going to mouse over an air terminal or a piece of duct.

It doesn't really matter. And hit tab twice, and that's gonna select all of the ductwork in that unit, in that system. And I'm going to say duct pipe sizing, and I want the friction the sizing method to be friction. I like point o eight inches per 100 foot. Obviously, change it to whatever you want. You can choose to also slice it size it for velocity. And then you can also have some constraints like restrict the height. Like, I don't want this to be any higher than 14 inches, that sort of thing. You have a couple of options in here that you can play around with. But once the settings once you've got this set the way you want, you pretty much just hit duct pipe sizing.

This pops up, and you hit okay. And then it will size the duct according to the way it thinks it should. You know what? I'm gonna just control z that real quick just so that we can see what's going on here. So this says that the friction here is point o six inches, and the friction here is actually at point two two. So, obviously, that that's, you know, quarter of an inch per 100 foot. That's not what we want. That's much higher than what we want. So we this is way undersized. This branch duct is looks pretty undersized 12 inches. That's that's pretty undersized, it looks like. So come back here, select everything, duct pipe sizing. This is all good to go. Hit okay. It sizes things.

So now the the branch duct sizing, it took it down to 10 inches. We can see that it's point o six seven seven. That seems to make sense. This is at 0.063, and this is at 0.0758. So that's much nicer sizing going on. Now, of course, if we if we wanted to make some changes to this, to the duct sizing, just because of what we knew what was going on, Easy easy to do, but the duct sizing tool is a quick and easy way to get your system in the ballpark quickly. Alright. That's it.