In this three part blog series, we will examine three different types of heating sources commonly used to supplement a central furnace in residential spaces. Part 1 discussed electric space heaters. Part 2 focused on wood stoves and pellet stoves. Part 3 will discuss fireplaces. Each blog will offer insight on the following: How safe are they? How much money can be saved? Are they environmentally friendly?
Part 3: Fireplaces
Admired primarily for their aesthetic qualities, traditional wood-burning fireplaces are regarded as being notoriously inefficient when it comes to heating a home. In fact, a fireplace may actually remove heat from the house by drawing in cold air from the outside through leaks surrounding windows and doors. Roughly 90% of the heat generated in a conventional fireplace travels directly up and out of the chimney instead of into the home. At best, a conventional fireplace is probably a mere 10% – 15% efficient.
In part 2, we discussed choosing firewood. Below is a handy little poem on the subject:
The Firewood Poem by Lady Celia Congreve
Beechwood fires are bright and clear
If the logs are kept a year,
Chestnut’s only good they say,
If for logs ’tis laid away.
Make a fire of Elder tree,
Death within your house will be;
But ash new or ash old,
Is fit for a queen with crown of gold
Birch and fir logs burn too fast
Blaze up bright and do not last,
it is by the Irish said
Hawthorn bakes the sweetest bread.
Elm wood burns like churchyard mould,
E’en the very flames are cold
But ash green or ash brown
Is fit for a queen with golden crown
Poplar gives a bitter smoke,
Fills your eyes and makes you choke,
Apple wood will scent your room
Pear wood smells like flowers in bloom
Oaken logs, if dry and old
keep away the winter’s cold
But ash wet or ash dry
a king shall warm his slippers by.
Fireplace Efficiency Tips
- Make improvements to the home’s insulation, seal cracks and weatherize around doors and windows. Sealing the building envelope will help prevent cold air being drawn in from outside.
- Keep the damper closed when the fireplace is not in use. The damper is the metal plate that regulates airflow through the chimney. Most dampers warp within a year or two. A better option is a chimney cap damper that closes the entire top of the chimney.
- Glass or metal doors placed in front of the fireplace are intended to be kept closed when the fireplace is not in use. When the fireplace is in operation, glass doors should remain open if possible to allow the radiant heat from the flames to enter the room without being reflected off the glass.
Firebacks and Heat Exchangers
There have been a few innovations that are said to be able to increase a fireplace’s heating efficiency. A metal fireback, for example is a heavy sheet of metal, usually made of cast iron or stainless steel, which sits in the rear of the fire box and radiates heat from the flames into the room. They are also claimed to be able to protect the masonry from damage caused from intense heat over time. Stainless steel firebacks are not intended for use with gas fireplaces as the extra heat they produce can damage the shut-off valve.
Another low-tech solution to improving traditional fireplace efficiency is a fireplace heat exchanger. These devices can take many forms. Generally, metal pipes are bent into a C-shape, forming a grate and placed inside the firebox. The fire is built inside the cradle of the grate. Air is blown into the bottom holes of the grate with a small motorized fan. The fire heats the air inside the pipes as it makes its way to the top. By the time it exits the holes at the top of the pipes the air has captured a significant amount of the heat from the fire as it is blown back into the room.
The most efficient fireplaces are heat-circulating fireplaces. Heat-circulating fireplaces work in a similar manner as the heat exchanger. Cooler room air is pulled in through a lower inlet. The air is heated by the firebox and naturally forces its way out through an upper vent where the heated air reaches the room.
Although more expensive than the other low-tech efficiency upgrades, a wood-burning fireplace insert is far more efficient, safer, cleaner and less harmful to the environment. An insert is basically a wood stove or pellet stove that can fit into an existing masonry fireplace. EPA-certified inserts are very efficient and produce relatively few emissions.
Though wood burning stoves and fireplaces share many of the same safety concerns, fireplaces may be slightly more dangerous. Be sure to have your fireplace and chimney inspected and cleaned by a licensed chimney sweep before each and every burning season. Follow these important safety guidelines to minimize the risk of fires and burning accidents.
- Visit the Chimney Safety Institute of America website.
- Keep anything that can burn at least 3 feet away from the appliance.
- Never leave a fire unattended. Always extinguish the fire before going to bed or leaving the house.
- Use fireplace metal mesh screens to prevent sparks and embers from flying out of the firebox into the room, possibly igniting something.
- Open glass doors while burning.
- Close glass doors when the fire is out to keep air from the chimney opening from getting into the room.
- Have your fireplace and chimney inspected annually before every heating season by a CSIA-certified chimney sweep.
- Make sure the flue open when using your fireplace.
- Only use wood that has been properly seasoned.
- Make sure to have functional, non-expired fire extinguishers in easy-to-find locations.
- Make sure all smoke alarms have fresh batteries. Test them monthly.
- Ashes should be cool before putting them in a metal container. Keep the container a safe distance away from your home. Douse and saturate the ashes with water.
- Never use flammable liquids to start a fire.
- Build smaller fires that burn completely and produce less smoke.
- Never burn cardboard boxes, trash or debris in your fireplace or wood stove.
Every home and space is different. If you have a small space and a limited budget, any one of the hundreds of kinds of electric space heaters might be for you. Traditional fireplaces are reserved for the ones longing for a certain ambience. You might not mind chopping, seasoning, hauling and storing firewood. Finally, there are the folks who can afford to install a heating stove in their home where they can simulate the ambience of a traditional fireplace while enjoying more efficient heating.