Closing vents in unused rooms - Bad or OK?

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Old 01-02-10, 07:08 AM
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Closing vents in unused rooms - Bad or OK?

I once read that you shouldn't close vents in rooms you don't use because it puts extra strain on the furnace and could damage it over time. Because of this I haven't been closing off the vents in 2 rooms in my house, but it seems like a silly way to engineer a furnace, so I'm curious, is this really a problem, or have I been led astray?

Any advice?

Thanks!
 
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Old 01-02-10, 07:37 AM
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It is bad. You are cutting down on the air flow across the heat exchanger in the furnace, and also air across the coil in your air conditioning.
 
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Old 01-02-10, 08:45 AM
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Well, there you have it. That's the information I was looking for.

Out of curiosity, why are vents built with the ability to be opened and closed then?
 
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Old 01-02-10, 08:57 AM
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Close too many warm air vents and the furnace can overheat, and perversely prevent the house from heating up on cold days.

There may be a margin which might allow a room or two to be shut off ---- or perhaps not. It really takes someone who can analyze what the furnace is doing to know.

Probably best not to experiment if you don't know.
 
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Old 01-02-10, 09:27 AM
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Out of curiosity, why are vents built with the ability to be opened and closed then?
One of those questions that the engineers don't want you to ask. I like to pick on engineers as you can tell. An easy solution is to create a register to open for every one you close. At least that way you are maintaining whatever balance is currently there. I deal with a lot of seniors who want to close everything except the one they are sitting on and have to find an easy explanation/solution for them. Adding a couple of registers, if you have access is not a big job, you just have to remember to use them in unison.

Bud
 
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Old 01-02-10, 10:00 AM
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One other thing....none of your interior rooms have insulation...so say you close off the vents and close the door to a room that has 2 outside walls with windows. That room will get cold...and the two adjoining rooms will also feel colder since there is no insulation between them. So now the fully open registers in the 2 adjoining rooms can't keep up with the heat loss.
 
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Old 01-02-10, 02:39 PM
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Wow... that's really great information! Thanks to all of you.

It really isn't that important to me, as I do use the rooms with some regularity, so I'll just leave the vents open!

Thanks again!
 
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Old 01-08-10, 07:05 PM
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Originally Posted by Gunguy45 View Post
One other thing....none of your interior rooms have insulation...so say you close off the vents and close the door to a room that has 2 outside walls with windows. That room will get cold...and the two adjoining rooms will also feel colder since there is no insulation between them. So now the fully open registers in the 2 adjoining rooms can't keep up with the heat loss.
True...plus if its cold enough and you have plumbing near the exterior walls of the closed room you run the risk of frozen pipes that can bust.
 
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Old 01-12-10, 08:37 AM
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also, if you have return grills in the rooms, they will be sucking in cold air from those rooms bring the efficiency of the entire system down.

When you close registers you also end up raising the static pressure in the supply ducts and more air starts slipping out of the cracks and joints in the ductwork into non-living spaces in ceilings and floors.

All in all, closing vents doesn't provide any positive results for most modern homes.
 
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Old 01-15-10, 05:21 AM
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just ran into this thread and found it very informative. I wanted to ask if it is okay to close the vents somewhat but not totally. And we are talking about forced air systems right?
 
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Old 01-15-10, 12:30 PM
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Well...no expert..but thats they way most people adjust between summer and winter settings unless they have dampers in the system.

You don't want to restrict overall airflow though.
 
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