Want to do a quick video and hopefully clear up some confusion that I see in the HVAC industry and I see this confusion with a lot of homeowners. But honestly, I see this confusion with some pros. And so as we dive into this I'm going to use some big words from time to time that a lot of heating and air guys use. but ultimately I'm going to narrow it down and make it very basic so that anyone can understand this concept.

And the concept we're going to be talking about is duct sizing and why Going from one size to another sometimes jumps dramatically when you're not really adding that much size. And so I'm going to be using a duck lator to help us go through this. If you like this duckator, it's actually my favorite one I've laid hands on. It's one of the more basic ones out there, but it's very userfriendly and I'm going to put a link to this Duc lator in case you want to buy it yourself.

I'm going to put a link to it down in the description of this video. but as we go through this I want to show you real quick? Uh, as as we go through this, we're going to be talking about a 6 in duct. We're going to go a little bigger here. so we're going to do an 8 in duct.

We're going to go a little bigger than that now and do a 10in duct. And then finally, we're going to be talking about a 12in duct. And ultimately, what we want to be talking about is when you go from say a 6 in to a 12in duct. Why it doesn't just double the Cfms or the amount of air flow that can go through that duct a lot of people think you know I've got to go from a six to a 12 to double the amount of air flow.

And what they don't realize is in most cases, just going from a six to an 8 in round duct actually doubles the amount of Cfms. Now there's more to it than that. there's static pressure and velocity and so on. but just keeping it mostly basic in most residential applications.

If we're doing a 08 or a 0.1 static pressure for our supply, you're going to be around 100 Cfms for that 6 in and around 200 Cfms for that 8 in. So let's let's kind of show you what that looks like on our duck lator here and that that's the way this duckator works. It kind of rocks Back in Forth And if we put our round duct diameter over here down to say 6 in. ignore all my my notes I've got notes here and you know all over my ductulator that helps us lay out duct work and things like that.

But if we put our round duct here at 6 in and you come over here to 0.1 or 8 whatever you use for your supply static pressure you're going to be around 100 Cfms. In fact most guys in our industry when they're laying out their duct work, that's what they're usually doing. They're saying okay in this room I'm going to do 100 and so I'm going to do a 6 in and then the you know, that's kind of how they do it. And of course we're talking about flex duct.

That's round. We're talking about the hard pipe. That's round. We're not talking about the square stuff.

I Know there's still states that they run square duct to every room, but hopefully you see what I'm saying there. So at 6 in, we've got around 100 Cfms. Now if we bump this up to 8 in, we're all the way up here above 200 Cfms now. Okay, and if we go up to 10 inch, so we just went from just a six to an eight, we doubled.

And now if we go up to a 10 inch, we're all the way up here above 400 Cfms. Now, if you're doing 08, you're just under that. But you get the idea. So just going from a six to an eight and then an eight to a 10, you have doubled and then doubled again.

The amount of air flow, the amount of Cfms that are going to go through that duct, and now finally, if we look right here, if we go all the way up to say a 12 in now, we're going to be up in the neighborhood of just under 700 Cfms. If you're at 08, you're going to be around 600. So we're going to say 600 Cfms. So back to our chart here.

We got a six and eight, a 10 and a 12. Our six is going to be 100, Our Eight's going to be 200, Our 10 is is going to be 400 and our 12 is six times higher than that 6 in. now. Why is that right I Mean we see it on the ductulator, but why is that? Why if we're going from a six to an eight, why does it double? And if we're talking about doubling the diameter, why Is it almost six times higher than the original, right? And here's one thing I can show you Now we could talk about other things like velocity and static and friction and all the other things that guys throw around.

but I Want to just show you one quick illustration. Let's say we had a ruler here. So we got a ruler and we've got all of our inches laid out on our ruler. So we've got a ruler showing that that's that's 12 in in diameter from one side to the other.

If we were to take one of these 6 in and fit it inside here, so there's the middle and so now we've got a 6 inch here and now we're going to do another 6 inch on this side. So we've got two 6in pipes that would fit in there right The the diameter would fit right. What? I want to show you is all this right here that's not being used and again, we're not talking about all the other crazy things when we're talking about air flow and velocity and all the other big words that heating and air guys use. But I think if you look at that illustration right there, that will show you ultimately why just doubling the diameter doesn't just double the Cfms? Just going from a six to an eight, you're doubling the Cfms and going all the way from a six up to a 12.

You are adding six times the amount of air flow through that 12in on a supply side duct work. So maybe that'll kind of. you know if you've do got a a heating an air guy talking to you. if you're a homeowner about, you know, duct sizing, maybe that illustration hopefully can, kind of.

you know, break it down a little bit, make it a little more basic for you to understand. Let me know your thoughts down in the comments section I'd Love to hear that if you like this video I Think you'll like this one even more. It's where we talk about three issues that duct work has that homeowners should know. Thanks for watching.

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