Should Vents In Unused Rooms Be Open or Closed in Winter? It Depends

LESLIE: Evan in Florida is on the line and has a question about vents in unused rooms. How can we help you today?

EVAN: Well, my wife and I have a long-standing disagreement on what’s best during the winter months for vents in unused rooms.

TOM: OK.

EVAN: I say close them but she says leave them open.

TOM: You both might be right.

LESLIE: Everybody wins.

TOM: Yeah, if you close …

EVAN: Oh, no. That’s not going to help us out.

TOM: That’s not going to help you out? If you close the vents in some rooms, especially if it’s anywhere near plumbing, you may have the temperatures drop to the point where freezing is an issue.

EVAN: OK.

TOM: But generally speaking, I think you can close those vents in unused rooms if you’re truly not going to use them. But it might be better to close them, actually, closer to the air handler itself or the furnace itself because a duct damper is much more efficient than the wall damper. The wall – the vent itself, once you close it, it tends to whistle and a lot of air leaks through it.

EVAN: Oh, yeah.

TOM: But in line with the ducts themselves, they should have dampers, too, which are more like sort of a valve for a duct that sort of totally closes off the air to that space.

EVAN: OK. Yeah. Seeing as – in line this was and they’re a little different.

TOM: Yeah, they’re a little tricky. There’s usually a rod that goes through the duct. And if you look at it, it’s got a flat on the end of it. It’s only – it’s very narrow; it’s like the size of a screwdriver tip. But if it’s parallel to the duct, then it’s fully open. And if it’s perpendicular, then it’s fully closed.

EVAN: Alright. OK. That solves our issue but I don’t know if I should tell her I’m right or wrong. I don’t know.

TOM: It didn’t settle the bet. It solved the problem but didn’t settle the bet. But like Leslie said, “Everybody’s a winner today.”

LESLIE: Everybody’s a winner.

EVAN: There you go.