Don't close supply vents in unused rooms. Your HVAC system is designed around specific airflow paths, and blocking vents forces the fan to work harder and can pull unconditioned air from unwanted places like attics or crawl spaces.
Questions this video answers
Never — do not close supply vents in your house.
You can close the door only if there is enough clearance (undercut) or another return path so conditioned air can reach the return; otherwise do not close it.
Chapters
How often should I close the vents off in rooms that I don't use?
Yeah, I get this question quite a bit. You should close the vents off. Never, ever, ever close the vents off in your house. Your house is made and designed to condition with those amounts of grills or runs in that room or in that space. So you should never close off that room, close the door to that room. Well, I'll take it back. You can close the door if you have enough room for the air to get back to the return. So you, and some houses and they have really thick carpet, you close the door and you have to kind of slam it shut. Okay, well, air is going to have a hard time getting through that space. And some homes have a good undercut under the door. So you close it and the air still flows out. So what goes in must come out. Same thing here with air. If it goes into the house, it must come back to the return. So you want to make that as easy as possible because air is like water again, it's going to get, it's going to get the air. You want to get it clean conditioned air versus air from outside crawl space through the walls. You can't control that unconditioned air. You can control the air in your house. But to get back to the vents, yes, never ever close the vents. So the reason you have vents on the outside of your house is because it's trying to take care of that perimeter. So you don't see, unless you're sitting in a mobile home, has two tracks of duct system, you will not see a grill on the inside wall in your house because it wants to take care of the perimeter outside wall that is affected by the weather. So closing off the grill affects, that also affects the airflow going into the room. So if I have a split unit and my fan coil is blowing the air out and where it's blowing to, can I get out, what is air going to do? It's going to try to come back maybe. So that fan has to work harder to push it back out because it's getting some resistance because the vents closed off, that's going to cause a problem. So if the fan has to work harder to get the air to where it needs to go, is it saving you money or costing you money?
