What’s the Difference Between Coaxial and Colinear Venting Systems?

Coaxial and colinear venting are two different types of venting systems that are used for direct vent fireplaces. Both systems are designed to provide an efficient and effective way to vent exhaust gases, but they work in slightly different ways.

Coaxial venting systems use a design of a pipe within a pipe. The inner pipe carries the exhaust out while the outer piper delivers the fresh intake air to the hearth appliance . This type of venting system is known for its compact size, physical stability, and its ability to provide a direct path for exhaust gases to escape.

 Colinear venting systems use two pipes arranged side-by-side. One for the intake of fresh air and one for the exhaust of combustion gases. This type of venting system is known for its ease of installation in tighter, non-combustible spaces.

Coaxial and colinear venting systems are used for different applications. Rigid and flexible coaxial venting systems are typically used for fireplace applications where there are combustible materials (like wood framing) around the fireplace. Whether venting out of the rear of the fireplace or venting vertically through a roof, coaxial direct vent pipe offers a variety of solutions to install the gas fireplace properly.

Colinear venting systems are almost always used for a direct vent gas insert. These hearth appliances must be installed into a wood burning fireplace where space is often at a premium. The flexibility of colinear venting systems allows the unit to be positioned correctly and vented up through the chimney.

In summary, the basic concept is that a coaxial vent system is used for a direct vent gas fireplace application while a colinear vent kit is used for a dv gas insert. As always, consult with an NFI Certified Hearth Professional with any questions about which of these systems are right for your project.