Ventilation Problem

November 30, 2009 11:03 AM

How do I determine why vent is not sending heat & A/C to one bedroom?

Have a 3 bedroom house. 100-years old if that helps (A/C is brand new, furnace is probably 40+ years old).

2 bedrooms (the 2 larger ones) have vents that work fine. The 1 small bedroom only has 1 vent: absolutely no heat or A/C comes through this vent.

Where do I begin to figure out what the problem is?

posted by glenngulia to home & garden (7 comments total)

Find the ductwork and check all of the dampers. The handle on the damper usually is in the same position as the "fin" inside of the damper.

That is where I would start. I would guess a closed damper.
posted by Danf at 11:13 AM on November 30, 2009

When's the last time you had your ductwork cleaned, too? We had ours cleaned for the first time ever and it drastically improved the airflow.
posted by lizbunny at 11:15 AM on November 30, 2009

Yes, check the dampers.

Seconding lizbunny's observation--I also had the ducts cleaned (for the first time in the house's nearly sixty years of existence...), and was stunned by how much the efficiency improved.
posted by thomas j wise at 11:22 AM on November 30, 2009

Another thing. . .check the filter(s). Possibly a plugged or dirty filter is decreasing the flow enough to make it go away in that duct (esp if the duct in question is the furthest up the line).
posted by Danf at 11:23 AM on November 30, 2009

Our vents are in the floor and the ductwork is in the crawlspace under the house. There was a room that just wouldn't stay cool and it turns out the duct to the vent had become disconnected completely and fell down. The landlords hooked it back up and all was well.
posted by chiababe at 11:58 AM on November 30, 2009

If the AC is brand new it's possible that the installers neglected to reconnect some ducts. If it's a one-story house with a basement go down to the basement and check out the ducts. You should be able to figure out which rooms they're going to. If the house has two stories it can be trickier.
posted by mareli at 12:02 PM on November 30, 2009

Some good suggestions above.

If there is a vent that goes in to the room is there also a return vent for air to leave the room? If there is only a vent going in, then the door to that room would have to be open for hot or cold air to circulate into that room. The amount of air that can go in is equal to the amount that can go out. So the only amount of hot air or cold air that can go in with the door closed is what can leak out under the door or through some other crack. Even in modern houses and apartments you can get moisture problems in bedrooms if you don't leave the doors open at night.

Sometimes in older houses with central heating there is a vent in the wall or the floor that isn't attached to ducting, it just runs straight through the wall to the hallway or to a room below. If there is only one vent, it may be the case that there is a vent in the floor or wall that was removed or covered over.
posted by jefeweiss at 2:03 PM on November 30, 2009