Making Your Fireplace Much More Efficient

If you have a fireplace (or are considering buying a house which has a fireplace), you probably know how nice an amenity that a fireplace can be.  It is a wonderful place to gather the family and guests around, it provides warmth and can add stunning ambiance to your home.  But traditional wood-burning fireplaces are not energy efficient, and if not operated properly, they can be very dangerous. 

This article discusses:

• how a fireplace works,
• how to improve it’s energy efficiency,
• what typically goes wrong with fireplaces.​

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How A Fireplace Works

​Despite their appearance of being all warm and cozy, fireplaces tend to be very inefficient for home heating. In fact, the energy efficiencies of fireplaces typically range from only 10% to a minus 10%.  The reason the efficiency can be below zero is that the fire draws in heated air from inside the home and vents it up the chimney.  In other words, most traditional fireplaces remove more heat from a home than they actually produce!
 
The major components of a fireplace are the firebox, the chimney, the fuel supply (wood) and the air needed for proper combustion.  To see a diagram showing the components of your fireplace system (for example the flue liner, ash door, damper, smoke shelf, etc.), see the diagram below.
 
A running fireplace needs constant airflow and fuel.  As the fire runs, the hot combustion air goes up the chimney, which rises because the hotter air is less dense than the cooler air outside of your chimney.  It’s important to note that all of the air that goes up your chimney has to come from inside your house.  For an average fire, this is about 300 cubic feet per minute of air . . . which is the equivalent of three good size bathroom fans all operating at the same time.
 
So where does all of this air for your running fireplace come from? Well, it comes from openings in your home, such as your bathroom and kitchen fan vents, and all of the small openings around your doors, windows, and around pipes penetrations of your walls. And this means on a cold winter day, when your fireplace is running in one room of your house, that it is pulling in 300 cubic feet per minute of ice cold air from outside your house into the other rooms where you have vents, etc . . . and since these are in areas away from your fireplace, it means that your central heating system has to work harder to heat up all of this in-coming cold air.
 
Here are some basic operating tips for your fireplace:
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• Slightly crack open a window that is closest to your fireplace, so that the fireplace can get the air it needs in the room where it will be heated up by the fireplace (rather than bringing cold air into other areas of your house, which then have to be heated by your central heating system). Also, by cracking a window in the room, it will help reduce the chance of smoke coming back into your house during start-up, when the air in your chimney is cold, and the heated air hasn’t started a strong enough draft to carry the smoke up the chimney.
• When starting a fire, use small pieces of kindling wood, rather than a lot of newspaper, as paper can create flaming scraps, which can be carried up and onto your roof (see types, costs, and reviews of kindling wood). Place wood criss-crossed above the light kindling, to allow easy air flow. 
• Build fires in the back of the firebox, to help keep the fire from falling out of the fireplace.
• Make sure the damper is open before starting your fire, and then close the damper when the fire is completely out.  Leaving the damper open when the fireplace is not in use allows cold air to come down your chimney and into your house.
• Never use gasoline, lighter fluid or a butane torch to start a fire.
• If your fireplace is equipped with glass or metal doors, make sure they are closed before you leave a fire unattended.
• Firewood can attract termites into your home, which can do thousands of dollars of damage, so you will want to store your firewood at least 20 feet away from the side of your house. And to help keep termites and other pests from infesting your wood, your woodpile should be supported at least 5 inches from the ground by non-wooden supports, such as concrete blocks, metal rails, rocks, etc.
• Your woodpile should be kept covered at all times to keep rain and snow from dampening the wood (helpful accessory: wood pile covers). But don’t wrap it tightly, or this will keep the wood’s moisture from evaporating and will delay the seasoning (drying) process.
• If you store some of your firewood on a storage rack inside of your home, you should carefully inspect wood thoroughly for bugs before you bring it inside (helpful accessory: firewood racks).  And then this indoor area needs to be inspected from time to time for any signs of pest infestations.  You should always burn only “seasoned” firewood