When flying we'll usually hear the Captain speak about the stratosphere. It's a layer of the atmosphere above the troposphere. What is happening in our atmosphere is stratification, the layering of varying temperatures and densities of air. This same physical principle is applicable to our homes, except it is undesirable when it occurs.

Through the lens of an infrared camera these air layers can be observed. In my experience this will happen almost exclusively with forced air heating and cooling systems. But it also is common in high ceiling rooms, regardless of heating / cooling system variety.

In the first infrared image a distinct temperature differential can be seen between the floor and ceiling. The warm air expelled from the ducts is layered at the ceiling over the colder air at the floor.

This was taking place through out the entire second floor of this home. The reason was basically the duct placement in the rooms. The ducts had been installed high on the back walls opposite the exterior walls. This placement blows warm air straight across the ceiling causing it to stratify.

The second image is similar to the first. The heating duct is in the ceiling at the top right of the picture. That's a big screen TV below the duct. The TV is about 10 feet away from the duct. You can see the layering very clearly on the screen and the walls on the left.

The temperature differential here is about 12 -14 degrees floor to ceiling. Again duct placement is the primary culprit. This duct is in the ceiling in the center of the room. It is not effectively distributing the warm air through out the room.

A simple solution to these respective problems could be ceiling fans if practical. The TV room would be a problem, but the other room it should be possible. Ceiling fans move air very effectively using little energy. In the winter the fan should be set to run clockwise to blow the warm air off the ceiling. When standing under the fan you should not feel a breeze if it is set correctly.

A more involved solution would be to move the ducts or at minimum, again if feasible, install deflectors on the registers. Here in the Northeast we use heating more than cooling and as such ducts should be placed, if at all possible, in the floor, not the ceiling.

By homogenizing the air in these homes, it will cause the heating systems to work more effectively and efficiently and as an added bonus the rooms will feel more comfortable.

So the next time you're flying and you hear the Captain talk about the stratosphere, you'll  appreciate that outside the plane is where those air layers belong.

James Quarello
JRV Home Inspection Services, LLC

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