What is a Direct Vent Fireplace?

Category: Fireplace

A cold home is the last thing you want to deal with on a winter night. So you might cover yourself in flannel pajamas to ward off the chill, brew yourself a cup of hot cocoa, or, if lucky, you might curl up next to a warm gas fireplace. However, you lose heat through the chimney if your gas fireplace isn't a direct vent fireplace.

direct vented fireplace

Today, the majority of gas fireplaces that are manufactured or built in factories are direct-vent models. Most fireplaces in houses constructed in the last 20 to 30 years use these energy-efficient venting systems instead of more antiquated ones. Additionally ideal for use in remodels or room additions, these fireplaces. Considering installing a direct-vent fireplace in your house? Discover more about these fantastic products by reading on.

How Does a Direct Vent Fireplace Operate?

The direct vent system was invented in the 1980s and is currently the most popular venting technique. Because of its effectiveness, safety, adaptability, and lack of need for an existing chimney, it continues to be a popular option.

Direct-vent fireplaces are enclosed fireplace units that draw in outside air while exhausting combustion byproducts inside the building. Coaxial and colinear are the two main varieties of direct vent fireplaces. The first kind, called coaxial, consists of a pipe inside a pipe, with the outer part acting as an intake and the inner tube acting as an exhaust. Colinear direct vent fireplaces have two pipes lined up, one serving as a dedicated intake pipe and the other as a dedicated exhaust pipe.

There are several advantages to the two main direct venting designs. Each avoids problems like a lack of oxygen and a bad drought. These fireplaces also function well when subjected to stringent energy efficiency requirements.

But exactly how does it operate? In direct vent fireplaces, two rigid flue pipes that fit inside one another are installed in sections ranging in length from 4" to 48", with 90° and 45° angled elbows to provide placement flexibility. An outer flue with a diameter of 8" or 6 5/8" surrounds a 4" inner flue.

The flue pipe is a duct pipe used to vent or exhaust gases outside the house. Combustion results in the production of harmful substances like carbon monoxide. The flue pipe's function is to evacuate your home's interior from dangerous combustion byproducts. Carbon monoxide can dangerously accumulate inside the house if the byproducts are not properly ventilated.

The outer pipe draws in fresh air for combustion and transmits it directly to the bottom of the sealed firebox, where it ignites the unit, while the inner pipe exhausts to the outside when the gas fireplace is turned on. The outer pipe also aids in shielding nearby combustible elements from the heat transferred through the system.

Any flames or combustion byproducts are completely isolated from the air in your home by a high-temperature glass panel and protective screen that seals off the direct vent fireplace unit from the interior.

Fundamentals of a Direct Vent


Improved Design

A sealed intake and exhaust are features of direct-vent fireplaces. For an effective design, these units draw air from outside the house, exhaust to the outside, and radiate heat inside. As a result, direct-vent fireplaces are less affected by air pressure changes and draughts than traditional fireplaces.

Venting Systems

Depending on the installation requirements and the manufacturer's recommendations, direct-vent metal ventilation ducts can be rigid or flexible. To avoid obstacles or cover large distances, these vents can be powered-vented, routed through an exterior wall, or exit the roof. No masonry chimney is necessary for a direct vent installation, but you must keep clearances to combustibles according to the manufacturer's guidelines.

Electrical Concerns

Most direct-vent fireplaces run purely on gas and don't even need electricity to function. A secure construction is made possible by a standing pilot light and a straightforward, dependable millivolt valve system. However, for features like blower fans, lights, or electronic ignition systems, a source of electricity may be necessary for newer or more sophisticated direct-vent fireplaces.

Additionally, the Intermittent Pilot Ignition (or IPI) found on most new units uses electricity to light the pilot light and start the appliance. After use, the pilot also turns off to conserve fuel and put out any remaining flames.

Direct Vent Fireplace Installation

To ensure safe operation, a trained professional should install direct-vent fireplaces. For direct vent configurations, always check the appliance manufacturer's website. It's important to remember that each fireplace will have a specific venting system that needs to be used to ensure proper installation.

Once more, a licensed installer will simplify this process, but each fireplace's manual will contain specifications and diagrams outlining venting options. Although direct-vent systems are straightforward, we know that each installation can have its variables that can present particular installation challenges. Because of this, it is suggested to consult a certified installer.

How Efficient Is a Direct Vent Fireplace?

Direct-vent fireplaces are energy-efficient for several reasons, including that they provide their heating and do not need to draw heat and air from the surrounding space. Because of this, some of these units function at up to 70% efficiency. Additionally, compared to conventional or decorative vented gas logs, which lose most of their heat through the chimney, these fireplaces are significantly more energy-efficient.

Benefits of a Direct Vent Fireplace

Combustion occurs in the home with a traditional gas fireplace. Burning propane or natural gas requires indoor air to be expelled up a flue. A flue is a vertical pipe that ejects gases naturally by pulling them up and out of the building through the roof. Warm air rises naturally above cooler air, so the hot gases rise through the flue and outside.

Traditional gas fireplaces are inefficient because they let conditioned air leave the house through ports in the firebox and the open fireplace doors. Backdrafting may happen due to their design, for example, if a kitchen fan is sucking the air out of the house. As opposed to being expelled outside, harmful gases may be drawn back into the house by the depressurized indoor air.

In terms of safety, effectiveness, and versatility, direct-vent fireplaces have several advantages over conventional gas fireplaces. A direct vent fireplace burns fuel with outdoor air rather than indoor air. It draws outside air through the outer chamber of a double vent pipe, and the inner chamber of this pipe exhausts fumes. The heat's natural flow creates a conventional loop; as hot air leaves the pipe, denser and cool air is filled in the area.


Backdrafting is not an issue with direct vent fireplaces because there is no need for a flue through the roof. Instead, you can install the vent pipe through the wall with a fire-caulked flange as an additional safety measure.


Like traditional fireplaces, direct vent fireplaces burn natural gas or propane, converting a greater portion of the fuel into usable heat. A glass door separates them from the interior rooms, preventing significant heat loss.


Direct vent fireplaces can be installed anywhere in a house because they can be installed through the wall. You can also vent these fireplaces upward through the roof if no wall space is available. Direct vent fireplaces come in wide widths and heights, despite tending to be shallower than conventional gas fireplaces.

Vertical is raising the bar when it comes to what a chimney and fireplace solutions company can be. Vertical has been in the chimney care business for over 35 years, and we have devoted our time and energy to bring safety to your home. We have spent all 35 years making sure we give our customers the best possible service. Starting your project is easy, contact us today!

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