An interior fireplace can make the smallest of rooms feel warm and inviting, but few homeowners think they can install one without an existing chimney. Standard fireplaces usually require a chimney made from non-combustible materials, such as brick or stone, to push out gases and fumes that burn off. The downside to this style of fireplace is that it's costly, and often complicated, to add on to a house’s design once it has been built.
Thankfully, you aren’t limited to the design of the traditional fireplace and chimney. There are many fireplace models that can be installed into an older house without rebuilding its entire structure. A B-Vent, or natural vent, allows a gas-powered fireplace to be installed in more locations and styles.
What is a B-Vent?
A B-Vent fireplace uses a vent pipe that pushes smoke and fumes from a gas fire upward and out of the house safely. This ventilation system can be enclosed in combustible material safely, hiding it away from the eye like normal ventilation. It's also known for being relatively inexpensive and efficient, as it can produce more heat than many vent-free models. Many include a shut-off switch that automatically turns the fireplace off if it burns too hot or is on for too long.
Code Requirements for Installation
If you're planning to put a B-Vent in your house, it must be installed by the supplier or another experienced professional due to potential gas leaks or fire damage. Labor costs may be expensive depending on where you plan to install it, as it's often hidden behind walls alongside wiring, piping and/or drywall. Be sure that this fireplace is installed at least 4 feet away from any dry combustible materials, including curtains or furniture, and remove any combustible liquids or vapors from the room entirely.
The location of a B-Vent and fittings must be up to local housing codes, so plan accordingly!
Each B-Vent and fireplace model will have their own specific requirements, so review your fireplace’s manual and any resources provided by the supplier prior to installation. Before doing any installing, sketch out a general plan of how the pipe should be installed through each house level, and adjust as things change. Each B-Vent installation requires:
- Bends: The goal of installing a B-Vent throughout the house is to make it a straight line upward; however, you may run into obstacles already installed in the wall. This type of venting does allow for some bends in the design, but no more than two 90-degree bends or four 45-degree bends. If your chosen location requires more bends, you should relocate your fireplace insert until you have a clearer path for installation.
- Clearances: While you can encase a B-Vent in combustible material, you must allow for air space, or clearance, between the pipe and that outer material. Most housing codes require a minimum 1-inch clearance between the pipe and outer material, but refer to your manual to be sure.
- Framing and Support: If a B-Vent is piped through your ceiling, you’ll need to install a Square Firestop Support. This support requires some extra framing to be installed between a ceiling’s beams. Depending on the pipe’s diameter, you’ll need to make a square large enough to surround the pipe (with clearance) so the pipe can be supported with clamps before going up through another floor of the house.
- Termination: The termination of a B-Vent is the final opening of the ventilation system that opens to the outside. The required height of this termination point depends on the roof pitch. Pipes with smaller diameters, from about 3 to 12 inches, must end at least 2 feet above the nearest wall of obstacle once they reach about 8 feet high. Pipes that are 14 inches or more in diameter must end at least 2 feet higher once they reach about 10 feet high. Consult your specific fireplace manual, house blueprints and housing codes for more specific termination instructions.
- Penetration: When pipes from the B-Vent pass through the walls and interior of a house’s structure, it's called penetration. All B-Vents will have a minimum of two points of penetration: when the pipe enters the wall and when it exits the wall before termination. If housing design requires more penetration, and more exposed piping, be sure to provide the proper clearance for each area.
Make sure that a professional inspects your B-Vent fireplace before use to prevent fire damage and/or gas leaks.