Chimney and Venting Pipe Buying Guide
This guide will help you understand the different types of piping systems that are available and which one will work for your system. Chimney Pipe is the term used for wood-burning appliances and includes Class A chimney pipe and Stovepipe. Venting pipe is used for gas appliances and includes Direct Vent Pipe, Type B Gas Vent pipe, and Pellet Vent pipe.
Before any installation, it is extremely important to read the instruction manual to determine the venting requirements for your appliance. You should also check with your local building codes to ensure you are in compliance.
Class A Chimney Pipe
Class A Chimney Pipe is used for wood-burning fireplaces and stoves. It is also used when transitioning stove pipe through a wall or ceiling. It is often referred to as double-wall, triple-wall, all-fuel, or insulated chimney pipe.
It is composed of either double-wall or triple-wall pipe, although the most triple-wall pipe is becoming less prevalent. The inner pipe encases heat emitted from fireplaces and carries combustion particles outside. The space between the inner and outer walls function as an air jacket by insulating the chimney pipe and keeping the surface of the outer wall from becoming too hot.
It is important to NEVER mix and match different brands within one chimney system. Each brand is specifically engineered and must be used together from beginning to end. If the brand you have is discontinued or obsolete, unfortunately, you must start from scratch.
You will typically have a choice between galvanized steel (galvalume) or stainless steel. Since galvanized steel is cheaper, it makes sense to use it when it is not exposed (in the masonry, chase, attic, or an indoor enclosure). If the pipe will be exposed, it’s better to use stainless steel because it looks better, and galvanized steel will eventually rust and corrode if it’s exposed to the elements. If you do use galvanized steel outside, it is recommended to paint the steel with a high temperature, rust-resistant paint.
Example of Class A Chimney pipe: DuraVent’s DuraTech
Direct Vent Pipe
A direct Vent pipe is used specifically for direct vent gas or propane stoves and fireplaces. It is one of the most popular types of venting because of its efficiency and ease of installation.
Direct-Vent uses outside air for combustion and vents all exhaust back outside using either co-axial or co-linear piping.
The co-axial pipe is a pipe-within-a-pipe system. It utilizes a smaller inner pipe that is fixed inside a larger outer pipe, separated by spacers. The inner pipe (exhaust pipe) removes combustion by-products and vents the exhaust out of the appliance and home. The outer pipe (intake pipe) brings fresh air from outside for combustion.
Co-linear pipe uses two separate pipes, an intake pipe, and an exhaust pipe. This type is typically only used if you are utilizing an old chimney and if the fireplace manufacturer has tested it.
Example of Direct Vent Pipe: DuraVent’s DirectVent Pro
Stove Pipe is used for venting wood-burning stoves and should only be used in the room where the stove is installed. Once the pipe reaches a wall or ceiling, it must be converted to Class A pipe because the stove pipe does not have proper clearance to combustibles to go through walls or ceilings.
If you are converting through-the-ceiling, a ceiling support box or round ceiling support piece is required. If you are converting through-the-wall, a thimble required. Stovepipe is also referred to as a black pipe and a single wall pipe.
Example of Stove Pipe: DuraVent’s DVL and DuraBlack
Type B Gas Vent Pipe
Type B Gas vent is used mostly in older homes and isn’t as prevalent in hearth venting today. It is a double-wall metal pipe used for venting appliances with draft hoods.
Type B is less efficient than both the direct vent and vent-free units because it must terminate through the roof and could potentially blow cool air into the house if a downdraft occurs. Type B is also referred to as b-vent or natural vent.
Example of Type B Gas Vent Pipe: DuraVent’s Type B Gas Vent
Pellet Vent Pipe
Pellet vent is used for pellet or corn-burning stoves. These pipes have a small diameter (3-4 inches) and typically only require a 1-inch clearance to combustibles.
Pellet vents can be used from start to finish (can pass through walls and ceilings unlike stovepipe) and can be terminated horizontally or vertically.
Example of Pellet Vent Pipe: DuraVent’s Pellet Vent Pro
We hope this helps clear up some common questions about fireplace venting. If you'd like more information, give our helpful sales team a call at 888-977-6849.Shop Fireplace Venting