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January 2014 EnergyWiseSM Tip: Fireplaces

“Oh, the weather outside is frightful, but the fire is so delightful … .” That is, until you get your heating bill and find out burning wood to keep warn this winter does not save you any money. In fact, many uninformed people find that their cozy fireplace costs them more than if they had not lit a flame in the first place.

With soaring energy costs, the major drawback to having a fireplace has to be its inefficiency. When there is a fire going, the fireplace does indeed radiate warmth in its general vicinity, but it also creates a convection current that can actually pull warmed air out of the room and up the chimney. This may cause the home’s furnace to work overtime. This problem is compounded if thermostats for the regular heating system are not near the area impacted by the fire’s warmth. If the thermostat is not turned down while the fire is burning, the regular heating system will continue to operate and try and keep the ambient temperature up to the thermostat’s setpoint.

Another source of heat loss occurs when the flames have faded. When the fire is not burning, the fireplace has a damper which is supposed to block inside air from escaping and outside air from invading. The problem is that the damper is usually made of metal and has no seal, which means that heat continues to escape from the living space. To make matters worse, the damper is often forgotten and left open which allows even greater energy loss.

In addition to minding the thermostat and damper, there are additional steps that can help improve the energy efficiency of having a burning fireplace. Install glass windows in the front of the fireplace to reduce airflow up the chimney when it is not in use. This still allows the fire’s radiant heat and aesthetic appeal to be enjoyed.

Another step to make a fireplace more efficient is to simply find the nearest window to the fireplace and to open it a little. This allows the fire to draw colder air from the outside if it needs to, rather than drawing in already heated air from the living space. At the same time, if the fireplace is in a closed room like a den, doors to the rest of the house can be shut, making the room a closed system. An even better step to improve fireplace efficiency would be to install special intake ducting into the fire chamber. This intake can pull in air directly from outdoors rather than pulling it through the room from the nearby open window.

Make sure wood is dry or “seasoned.” Wet wood can create excessive smoke which is wasted fuel. Moisture meters that allow you to test the moisture level in wood are available and cost as little as $20. Properly dried wood should have a reading of 20% or less. In addition, the type of wood that you burn can make a difference. Wood that is hard tends to have the most energy per cord. Finally, consider installing a fireplace insert or wood stove. An insert is basically a metal wood stove that slides neatly into the fireplace cavity. They are relatively easy to install and can dramatically improve a fireplace's efficiency. Before adding one, however, make sure to have the fireplace and chimney inspected and cleaned.

Wood stoves usually provide the highest level of wood burning efficiency. While traditional fireplaces typically convert only 15% percentof the wood’s energy into heat, some wood stoves rated by the Environmental Protection Agency (EPA) can have efficiencies exceeding 70 percent.