What Different Gas Flue Chimneys Are There?

Balanced Flue

• Balanced flues have two layers. The first layer pulls air out of the atmosphere and into the fire while the second layer removes carbon monoxide from the fire and brings it outside, where it releases it into the atmosphere. Balanced flues can be installed internally either into the gas fireplace or into the fireplace's chimney. This kind of flue is often used with fireplaces that have a glass front or that sit on a hearth.

Fan-Ventilated Flues

• Inset gas fireplaces that don't have a glass front require the use of a fan-ventilated flue. Without this type of flue, carbon monoxide would escape into the room; this gas is toxic. Thus, a fan inserted into the flue helps circulate air and move carbon monoxide to the chimney, where it can be expelled into the atmosphere outside your home.

Modern Flue

• Ultra-modern fireplaces have a pre-cast flue made out of blocks. This flue is built into a cavity in the outside wall of the fireplace. This flue works like a regular chimney. The fire runs up the fireplace wall and gas goes through the flue and up into the atmosphere. The problem with this kind of flue is that many fireplaces aren't designed to work with it; you have to have a fireplace that is built for it.

Conventional Flues

• Some flues are similar to the flues used in conventional chimneys. Conventional chimney flues are about 7 inches in diameter and will fit many gas fireplaces. You can also get a smaller conventional flue, which is about 5 inches in diameter. Not all gas fireplaces work with this kind of flue because of its smaller size.