If your home-building or renovation plans include an efficient gas fireplace, take some time to plan the installation so that the fireplace can effectively contribute to your heating needs.
An efficient gas fireplace can lower a home's overall energy consumption and heating bills when located in a major living area where the heat has access to other parts of the house.
Install the fireplace in a part of the house where it will be visually attractive and where you and your family spend most of your time and will benefit the most from its warmth. This is usually on the main floor, in your family room, dining room, living room or kitchen.
The layout of your house will affect the fireplace's ability to provide heat to other areas of the house. If you are building a new home, consider a layout that focuses on the fireplace. An open design, where there are few walls to separate rooms on the main floor, will allow heat to move from the fireplace area to other rooms (see Figure 11). An accessible stairwell will also allow the heat to move upstairs (see Figure 12).
Figure 11 Open Design Concept with Direct-Vent Fireplace on Outside Wall
Efficient natural gas fireplaces can be an effective means of lowering heating costs and improving comfort levels in homes heated by electric baseboards. The baseboards in remote rooms can keep those areas at acceptable temperatures, effectively "zoning" the house, with the gas fireplace providing most of the ";comfort" heat for the rest of the home. A properly located and well-designed fireplace can meet over half the conventional-heating demands of a standard house while providing a visually appealing and comfortable atmosphere.
If your house's layout is such that the best location for a fireplace is against an outside wall, try to build the fireplace inside the house envelope. If this cannot be done, look for a fireplace with an insulated outer casing. Insulation is also important for a gas fireplace insert that is installed in an existing outside wall fireplace in order to eliminate direct heat loss from the fireplace through an outside wall.
Figure 12 Open House Design Showing Heated Air Circulation from Gas Fireplace
Another option to minimize heat loss is to locate the fireplace and chimney on an inside wall. By surrounding the vent with warm rather than cold air, you ensure better draft and reduce the chances of the house becoming a better chimney than the chimney itself (see sidebar on page 20).
If you must install a gas fireplace in the basement, a direct-vent unit is likely your best bet since it does not require a chimney. A direct-vent fireplace can be exhausted out the side wall of the house above the foundation, and it is sealed to prevent combustion exhaust spillage or the robbing of air for combustion from the furnace or water heater. Seriously consider insulating the basement before you install a fireplace there. As it will be more difficult to distribute heat, consider a low-input fireplace or a unit that can have ducts to transfer the heat elsewhere.
An operating chimney is an enclosed column of warm air or gases surrounded by colder outside air. The warm air or gas in the chimney is more buoyant than the dense, cold outside air, so it rises, producing natural vertical draft in the system.
In the winter, your house is also an enclosed column of warm, buoyant air that creates its own form of draft. In effect, the warm air pushes upward, creating higher air pressure at the top of the house and lower pressure in the lower levels of the house.
When an unsealed (non-direct-vent) gas fireplace has been installed in a home that has a lower pressure than outside, the house can become a more effective chimney than the fireplace chimney itself – especially if the chimney is located on an outside wall. Rather than using the chimney to release combustion gases to the outdoors, air can be drawn back under negative pressure into the home through the chimney. This reverse flow of air can cause spillage of combustion gases from a fireplace or other combustion appliances into the home, creating hazardous indoor air-quality problems.
Source: Natural Resources Canada (NRCan) - Office of Energy Efficiency