Derek ColeGM, Simmons One Hour Heating & Air · AI HVAC Answers

HVAC Secret: Why You MUST Keep Vents Open! #shorts

4 Mar 2026 · 1 min

Watch on YouTube

0:57

In this YouTube short, two speakers explain why residential HVAC vents and registers should never be closed to redirect airflow. They emphasize that closing vents raises static pressure, forcing the blower to work harder, and that ductwork is sized for a fixed airflow (e.g., a 6‑inch duct designed for about 100 CFM). Consequently, shutting off vents in one room does not increase airflow to another; the system cannot exceed its designed capacity. The overall message is a clear, cautionary instruction to keep all vents open for proper HVAC performance.

Chapters

Do not close your vents or registers in one part of the house to redirect cool or warm air to another part of the house. Just about any HVAC technician you talk to is going to tell you exactly that.
Never ever close the vents off in your house. The gentleman goes on to state how, um, mainly it's a static pressure issue. Yes, static pressure is a factor in not closing your vents. That's true because you're causing more air to go go back to the blower and then it's working harder to push it out. But mainly, people close vents because they're trying to redirect air to a place they're not at to a place they are at. Your duct system does not work in that fashion. A 6-inch run of duct in a room is made for 100 CFM of air. It can only hold 100 CFM of air. So if you close the vents off in the room next to it or the room down the hall, more air is not going to come through the 100 CFM vent.