Heat and A/C vents

[Dennis McDonaugh]

I have one bedroom which gets very warm in the summer. I don't think the air flow is as good as it is in other rooms. How do I go about adjusting the air flow to the room? I went into the attic and we have several boxes with the flexable conduit connecting them to the different air outlets throughout the house.

[W Craig Wilson]

You don't say anything about the orientation of the hot room. If it gets full Texas sun all day long, you may never get it comfortable. You also don't say if this problem just appeared (new malfunction) or if it has always been that way (poor design / implementation).
In any case, go back to the attic and look a little closer. Make sure that the flex is intact and in shape - no tears, no kinks, still round in shape, tight connections at all joints. A kink or tear in this stuff will cause a lot of air to go places other than into the room. Those problems are easy to fix - that's what duct (not duck) tape is really made for. Then take a look at those distribution boxes. They may have 'balancing' dampers installed that can be used to limit the air flow into each branch. Look for butterfly knobs or small handles that would rotate a shaft. These often have a screw or lock nut to snug down to avoid wander. If the damper for the hot room has wandered closed, just rotate it about 90 degrees to restore full air flow. If the hot room damper is open, then you will need to rob other rooms a bit. Adjusting the dampers for rooms that are comfortable toward closed, you will make more air available for the hot room. You will need to sneak up on these adjustments - you do not want to cut off any room completely. (The pros use some measurement equipment either a magnehelic guage or an air flow balance hood to measure and adjust. Without the gear, you'll need to do some trial and error fiddling.)

[Ray Bersch]

Craig, your right on with all of your suggestions. Just a bit of a correction about the duct tape - the standard stuff we buy at the local hardware store and the borgs is not suitable for taping HVAC ducts as it will deteriorate over time. And the more the heat exposure, the quicker the deterioration. There is an HVAC grade of duct tape that is meant for this purpose and I have seen it at some HD's but you have to look closely at the label to get the right stuff. There is also an aluminum tape for this purpose - which is what I prefer, and boy, if you think duct tape is sticky, wait till you try using the aluminum stuff!

BTW - the original "Duck Tape" was first made during World War II to be used by the military to seal ammo boxes - it was not long before the average GI found it useful for everything from fixing rifle butts to wrapping wounds - and it was GI green. The name seems to have derived from the fact that it was water proof - duck tape - or so the story goes.
Ray

[Joe Pelonio]

If it's a sunny room, the duct run is long, and the size cannot be increased, then you could install a duct booster fan, such as this. Probably not available at the big box stores, but can get them online or at heating/AC supply, some varieties at Grainger.

[Lee Schierer]

One more thing not mentioned in any of the posts. Make sure the room has an adequate air return. If air can't get out easily, you will have trouble pushing air into a room. Make sure the air returns are adequate. If the room has a door, make sure there is an air return inside the room and that the system is not relying on the open door for air flow.

[Dennis McDonaugh]

Good questions:

Criag, the room has been hot all along in the summer and cold in the winter. There is some air flow out the vents, but not as powerful as other rooms.

Joe, The house is oriented north and south, this room is on the northeast corner and only has windows facing north. The heat/A/C unit is in the attic, about 25' from the room so the duct run is not that long.

Lee, there is an air return in the room, that's one nice thing about the house, each room has an air return the same sizes as the vents so the doors don't rattle.

I'm going to take Criag's suggestions and go back in the attic to take a look at the duct and boxes. I didn't see any handles sticking out of the boxes, but I didn't look at them that closely. I'll let you know what happens.