Insulated Pipe

Double wall fireplace pipe is also called insulated pipe or Class A pipe. This metal chimney pipe, which is listed by the Underwriter Laboratory as UL Approved Stainless Steel Class A Chimney, is the only pipe approved for fireplace chimney installations. Double wall fireplace pipe is actually a smaller pipe inserted into a larger diameter pipe.

Heat-resistant insulation is sandwiched in between the two layers of pipe. Double wall pipe is the only pipe approved for passing through walls, ceilings and floors. Insulated pipe is available in a variety of widths and in sections up to 48 inches.

Installation Types

Fireplace pipe insulation generally follows two or three types of installation. The first method is typical of single-family homes. Run the stovepipe from the fireplace and connect via an adapter at the ceiling support collar.

The ceiling support collar provides fire protection for the framing members. Stack the pipe from the ceiling support collar up and out of the roof opening to the appropriate height.

The second installation technique runs the insulation out of an adjacent exterior wall.
The pipes are then stacked up to the correct chimney height requirement. The pipe can be boxed in and finished to match the rest of the home.

The third technique is a variation of the first method. The difference is that the components enable a connection to slanted ceilings or cathedral ceilings. A bracket placed at the roof level provides support for the piping.

Another variation employed by some homeowners who have older fireplaces, is to run new chimney pipes up and out of their existing fireplaces.

Guidelines

Make sure that you install the proper size pipe. Do not change the pipe size or mix and match. Follow the manufacturer’s instructions and the local codes. Eliminate bend in the pipe where possible. Each time you insert an elbow in the pipe run, you create more resistance to air flow and reduce the operating efficiency of the fireplace.

Purchase the appropriate installation kit for the piping method you choose. For example, if you decided to run the pipe out a wall and up to the appropriate chimney height. The kit may include a wall thimble collar, a length of adjustable pipe, a stovepipe adapter and a roof termination cap. The pipe sections thread together for an effortless assembly. Although there are larger sized pipes, the typical inside diameters are 6, 7 and 8 inches.

To create a watertight installation on the roof, pry up the top half of shingles around the top of the opening and on the sides. Slide the upper part of the flashing/roof cap under the shingles and align with the opening. Apply roofing sealant under the flashing and the shingles and nail them into place. Make sure that the nail heads are covered with sealant.

All chimneys are required to extend a minimum of three feet above the point where the pipe protrudes through the roof. The fireplace pipe must also reach two feet above any object located on the roof or within a 10-foot radius of the chimney.