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Does a Furnace Really Dry Out a Home’s Air?

Cold weather is often accompanied by a drop in humidity levels. This is why people experience trouble with static electricity more often during the winter. Fortunately, we don’t often experience excessively dry winters in Eugene, and the drop in humidity usually stays within a pleasant and healthy range.

However, you may have heard that a furnace dries out a home’s air, potentially leading to air that is too dry during the winter. Is there any truth to this?

Atmospheric Combustion and Dry Air

The truth is that some types of furnaces can contribute to lower humidity levels. They don’t exactly “dry out the air” so much as they pull more outside air into a home, and this air is usually less humid than the air inside.

This is a result of the working of an atmospheric combustion furnace, which is a common type of older furnace. This kind of furnace has an open combustion chamber. The combustion chamber draws on the air in the house in order to allow the burners to work. As this air is pulled from the house, it leaves a vacuum that is filled with an influx of outside air. If this outside air is drier than the indoor air—which it often is during winter—it will lead to a drop in relative humidity. It also creates cold drafts.

Sealed Combustion Furnaces

Many newer furnaces do not have this problem, however, because they use sealed combustion. A sealed combustion furnace has a combustion chamber that is closed off to the rest of the house. It draws air from the outside through a PVC pipe. This means there’s no forced exchange of air with the outside. The furnace will not only keep the air from becoming too dry, it will also work at higher energy efficiency because it won’t lose heat through an open combustion chamber.

If you’re interested in installing a new sealed combustion furnace in your house, contact Comfort Flow Heating in Eugene, OR.

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