In this segment Derek Cole explains why residential HVAC ducts are often tapered—reducing in size along the run—to keep air pressure high enough to deliver sufficient airflow to distant rooms. He uses a garden‑hose analogy: narrowing the hose (or duct) forces the flow to travel farther. He notes that when ducts are not properly reduced, the far‑end rooms receive far less air, leading to temperature complaints such as a hot southwest‑facing room versus a cooler north‑facing room. The core message is that improper duct sizing causes uneven heating/cooling, and correcting the taper restores balanced airflow throughout the house.
Chapters
So if you go into like a Zaxby's or a Red Robin and you look up at the ductwork, you see a big piece reducing to a smaller piece, reducing to a smaller piece. Okay. A lot of homes we go to don't have that going on. What we're doing there is you're making sure you keep the pressure up as you go on. So the room at the end of the house with the end of the duct system is getting very little air compared to the one at the beginning of the run. So what happens is it's not reducing. So when we go back in there with the new duct system, obviously we're reducing to keep pressure up. It's kind of the same principle with a garden hose, okay? You turn the water on all the way, hold the hose up, you see the water come out, right? You put your finger over it, what does it do? It goes a lot further. Same principle with air. So you want to keep that pressure up to make sure it gets all the areas in the house equally and it's balanced out. And that's probably what's happening with your system. I cannot think of a home— I could be wrong— a home that I've been under that has probably had that reducing going on with the duct system. And they all have the same complaint. It's hotter or colder in this room at the end, or it's hotter or colder in this room with the most glass on the southwest side because it gets the most sun exposure. Well, that room needs more air than the room on the opposite side that's on the north end with the walls. Makes sense? You got more exposure here. So it's a duct problem.
