In this YouTube video, homeowner Megan describes a bedroom at the far left end of her house that remains cold when the heat is on and hot when the air conditioner is on. HVAC expert Derek Cole engages in a conversational diagnostic, asking about the room’s location, number of vents, airflow strength, and distance from the HVAC unit. Through these questions, Derek points toward a likely duct or airflow pressure issue caused by the room’s position at the end of a long duct run, suggesting that improper duct sizing, lack of balancing, or pressure loss may be responsible for the temperature extremes.
We have one room in our house that is always cold with the heat on and hot with the air on. Is it possible that we have a duct issue?
So the advantage to having Megan ask me a question for herself is that she's actually here. So let me ask you, where, where is the room at as far as the house?
It's on the far left side, like it's an end room on the end of the house. It has two exterior walls, it's a bedroom.
Okay. So you got 2 exterior walls in that room. How many grills or vents do you have? 2. 2. One on each wall? Mm-hmm. All right. So in the— you check the airflow, is it blowing out pretty good? Yeah. I mean, I can feel it. Each one? Mm-hmm. Is it far away from the unit? Yes.
The unit is on the other side of the house.
Right. So what's happening is This is in the crawl space, the duct. So when your husband crawls under there and looks at it, what he'll see is one solid piece of trunk line. 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. 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. I mean, you can seal your duct system to help it a little bit because you are losing some under the house, but it's still not going to be it, what it can be.
