How Using Your Direct Vent Fireplace
Can Cut Your Fuel Bill by 50%

There’s nothing like the warm glow of a fireplace when it’s cold outside. Just the appearance of a real fire flame can warm any living space. But a direct vent fireplace can offer a whole lot more.

When used properly, a direct vent fireplace can act as the sole heating source in some homes and save a bundle in home heating costs. In fact, a 25,000 BTU direct vent fireplace can heat up to a 1500 square ft. one-floor living space.

First, we’re not talking about any fireplace, but specifically a direct vent fireplace. Direct vent fireplaces operate differently than an open hearth fireplace. An open hearth fireplace (commonly called a B Vent) is characterized by a log set inside an open front masonry or rated fire box. A B vent is primarily for appearance, not for heating the space. It combusts the indoor air and can actually cool the air in living space. That’s because already heated air is drawn from the living space up through the flue or chimney to the outside.

Unlike a "B" vent fireplace, a direct vent fireplace is characterized by:

1. A solid glass door that isolates the burner and log set from the inside of the home.
2. A concentric flue. With this flue, an exhaust pipe sits inside the air intake pipe (a pipe within a pipe). Instead of combusting heated inside air, all of the combustion air enters the firebox from outside through the outer pipe. Flue gas emissions are expelled to the outside through the inner pipe. Most new fireplaces sold are direct vent, especially in new residential homes.

A direct vent (concentric) flue can be vented through the wall or roof with a single 7" or 8" hole. All of the combustion takes place inside of a self-contained box housing the burner and log set. The flame never "touches" the indoor air because it is isolated by a solid glass front. As the glass gets hot, soft radiant heat energy is emitted into the living space of the home that, over time, heats the surrounding air.

In reality, a direct vent fireplace is a heater, but is only about 70% efficient. Most are not even heater-rated. So, here’s the key to energy savings: Instead of letting your 100,000 BTU gas furnace(s) blow warm air into every room, nook and cranny of the house, why not just heat the room where you spend the most time? This is called "zone heating" and is a practical method to decrease your living expenses during the cold months.

I have a direct vent fireplace in the family room located on the main level of our house. This space is used for entertainment, reading and eating (since the room is attached to the kitchen and dining area). We spend at least 85% of our time in this area of the home during the winter. Two bedrooms, two bathrooms, a formal living room and an office are all connected to this space. As long as doorways are open to the main family living area, the fireplace will warm those areas also.

The first principle of thermal dynamics is "heat seeks cold". As long as there are cold pockets in rooms or adjacent spaces, the heat from your fireplace will attack those cold spots. It may take a bit longer than your furnace system, but over time your space will become warm and comfortable. A ceiling paddle fan can help circulate the heated air to adjacent living spaces.

This winter, keep your furnace(s) turned down or turned off more often and use your direct vent fireplace as your primary heat source. While we can’t guarantee that it will heat your entire home, it can dramatically lower your monthly heating bill. Give it a try.