We have a two story home with 3 bedrooms upstairs. Home is 7 years old. One of the bedrooms is always around 5-6 degrees Fahrenheit colder than the rest of the house (when compared to the thermostat temp). Currently it is the baby's room and we placed a heater in there to bring up the temp to a comfortable level. I would really like to find a better solution as when the baby is not in the crib anymore we would not want the heater in the room.

There is one vent in the room (which is also true for the other kid bedroom that does not have this problem). The difference between the two vents is that the cold room went is running inside the drywall of the exterior wall and the other room vent is in the floor (but still against the exterior wall, just not in the drywall). The temperature coming out of the went in the cold room feels warm so I know the heat is getting there.

My first thought was to adjust the air flow in the vents going upstairs by closing some of the other vents thorough the house. But I have read that doing this will make your furnace work harder and less efficient since you are altering the origional design/installation. We are the second owners of the house and I am not sure if the room was originally not insulated properly, but I would prefer not to have to open up the walls if it is possible.

  • I have a similar problem, @Milos. This room wouldn't happen to be directly above a poorly-insulated garage, would it?
    – Sampson
    Jan 14, 2011 at 4:24

4 Answers 4


For a quick and dirty fix, I have had some success with a Register Booster Fan. booster fan pic

This has alleviated most of the problem in my house. I still plan to install more insulation (and upgrade to a multi-zone system), but this is a lot less work up front. You can use it as a stop gap until you figure out what permanent fixes you need to make.

  • Can you mount it on a wall? The register went is inside the wall about a foot high. Dec 2, 2010 at 14:14
  • Yes, mine are actually wall mounted. I believe the one I have came with some foam-backed adhesive double sided tape to attach it to the existing vent cover. Dec 2, 2010 at 16:53

I would suggest getting a thermal inspection done of your house. They can determine where the heat loss is occurring, and you can determine if the room was not insulated properly without ripping open the drwyall. Or you may find out that it is a gap around the window and it is letting in a cold breeze.

  • 1
    I am also planning on re-caulking the window. The thermal inspection is a great idea. Dec 2, 2010 at 14:25

Your better equipped hardware stores or contractor suppliers should have a thermal scanner for rent. The new ones are simple to use. It's just like pointing a small video camera at the walls and looking at the screen to see if there is a temperature difference indicated by a change in colors.

I suspect the space between the studs with the vent was not properly insulated. If you have access to the space above the room, you might want to check for air gaps in the space between the wall and rafters letting in cold air. Those would be pretty easy to close with an expandable foam.

Electrical outlets on exterior walls are also sources for cold air infiltration because builders don't always do a good job of sealing the outside of the box holding the electrical wires.

  • I will look into where I can rent a scanner around here. Dec 2, 2010 at 14:25
  • Earlier this fall I took the vent cover off and noticed a cold breeze coming in from the space between the drywall opening and the vent. I sealed all around the vent with expanding foam and the breeze is gone. While this helped I am guessing that you are right about the space between the studs not being properly insulated. Dec 2, 2010 at 14:29
  • You could also get one of those small fiber optic cameras. Drill a small hole into the wall and snake the camera through the hole and inspect the space behind the drywall without having to open it all up. You could also insulate the space the same way. Drill small holes at intervals up the wall - just big enough to insert a tube for expandable insulating foam. Fill the space with foam at each hole and let it expand into the space. The small holes should be easy to patch afterwards. You might have to do each side of the ductwork.
    – ChrisP
    Dec 2, 2010 at 14:41

Your symptoms -- a room far from the heating/cooling source is difficult to temperature-control -- are consistent with duct leakage. The first thing you should do is try to rule out a major leak by, as best you can, tracing the ducting running from your furnace (or air conditioner) to the uncomfortable room; look for a disconnected joint or a large hole that may have been created during construction which was never plugged or the repair has deteriorated. If you find no major leaks, the cause could be (and often is) the compounded effect of many small leaks – seams and junctions inherent in most duct work, an inadvertent drill hole during construction, and/or the small holes into which a damper is mounted. Believe it or not, all these small leaks typically add up to 20 to 40% of the conditioned air leaking out and not reaching its intended destination. The rooms farthest from the conditioning source – your furnace or air conditioner – suffer the most, simply a matter of more opportunities for leakage to occur as the length of the path and the number of turns/elbows increase. Aeroseal is an innovative sealing process that seals the ducts from the inside and, thus, overcomes the inherent difficulty for existing homes -- access.

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