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Cold air returns and supply lines - both high in room

Posted by stayathomedad (My Page) on
Sat, Jun 27, 09 at 16:04

We have a 6 year old home that is gas forced with a/c unit. Our first floor has heat registers in the floor. The second floor of our home has all of the registers in the ceiling.

Each room on the second floor not only have the heat/ac supply coming through registers located on the ceiling, but we also have cold air returns in each room and those are located high on each wall.

My problem is that it is very difficult to cool the upstairs. I am thinking that our cooled air is being blown in through the vents on the ceiling and being sucked right out by the cold air returns located high up on the wall. I know ideally that you would want a cold air return high in warm temps to pull the hot air out of the room, but that would be with your supply coming from the floor level, correct?

I was thinking of closing off the high cold air returns and cutting a low cold air return. Does anyone think that this would help with cooling the space?

I also believe that this is a problem in the winter as well. I think we suck the warm air straight across the room and right back into the cold air return.

Any idea or thoughts are appreciated. I have a searched all over the web and can't find anyone with the same problem.


Follow-Up Postings:

RE: Cold air returns and supply lines - both high in room

What you're thinking about doing would probably help some, but here's something to think about. When you go in a store, or a restaurant, the supply and return diffusers/grilles are also on the ceiling. So, it can work right if done right. I've been told that returns high or low should not make a huge difference in comfort, but ideally you're right, you'd want the returns low if supplies are high. Are the supplies and returns abnormally close to each other? Can you somehow direct the supply air toward the walls/windows (where it is supposed to be aimed toward anyway). I would try other options before going through the trouble to cut those returns. Could not be your major problem (is there a lack of airflow coming through the supply ducts? may be able to balance the system and direct more air where needed).

RE: Cold air returns and supply lines - both high in room

Where are your returns on the first floor?

If the conditioned cold air is coming out ceiling diffusers it will fall through the room (cold air is heavier than warm air). As it falls through the room it should push the warmer and lighter air towards the ceiling to be picked up by the returns that are high on the wall.

On the first floor your returns are probably in the floor also and that will cause the cold air to come out of the vents and go low across the floor and back into the return grilles.

In many installations if you have high returns in the wall, you also have low returns in the same wall cavity. They are designed to have the high ones open and the low ones closed for air conditioning, and then you open the low returns and close the high returns for heating. Do you have two vents in you wall, one low and one high, that are in the same stud space? If so that is how they are to be used.

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