Tips for Unheated Rooms
LESLIE: Celeste in Oklahoma is looking for some ways to be energy efficient this winter season. What can we do for you?
CELESTE: My question is – I’ve had two or three answers to this and I don’t know which is correct.
TOM: Alright, well we’re going to sort it out for you right now.
CELESTE: I shut off my floor vents and shut off the air; the warm air that comes into two bedrooms.
CELESTE: But then, when I go in there and decide I’m going to let it get warm, the air acts like it’s just trying to force its way out of that floor vent and I’m wondering if it’s more efficient – I can’t believe the air would back up and come into some other room. I just can’t – it just seems like the air is just trying to get out of that floor vent.
TOM: Well it is. It is, Celeste, because it’s a pressurized system. And by simply shutting off the louvers to that vent, you’re still going to get some air that gets through there. If you absolutely, positively want to sort of hermetically shut that off, there’s one of two things you can do. You can check to see if the ducts have a damper in them somewhere, which is sort of like an inline valve that closes the air flow.
LESLIE: But wouldn’t that be by your air handler that’s in the house?
TOM: Typically, yes. Typically. If …
CELESTE: Mine just has tin receptacles and I haven’t seen any sort of anything inside of it.
TOM: OK. Well then, the second thing you should do is this: you should pull – you said these are floor registers?
TOM: Is it a concrete slab floor or is it a wood floor?
CELESTE: We’re on a cement slab with carpet.
TOM: OK. So, alright. So what you want to do is pull the register out and then I would take some insulation – some fiberglass insulation – and I would roll it up and gently press it into that duct space to seal off the duct.
TOM: And then place the register back in and, this way, if you decide to heat the room in the future, you can pull the insulation out again.
CELESTE: OK. Well, often I heat it up but I just wondered which was more efficient.
TOM: Well, if you’re not going to use that room and you don’t care to let the temperature go down like that, then that’s a way you can do. I will tell you, though, if it gets too cold and too damp in there, you can get some swollen woodwork; you can get mold that grows on the wall.
LESLIE: Fabric is going to be a disaster.
TOM: Yeah. So just keep in mind that there’s a downside to completely sealing this off. But simply shutting off the register is not going to do that. You need to add some insulation or some foam padding behind it in order to stop all of the air from coming out.
CELESTE: OK. Thanks a lot.
TOM: You’re welcome, Celeste. Thanks so much for calling us at 1-888-MONEY-PIT.