Do Fireplaces Cause High Energy Bills?


The bad news is, winter’s on the way!  Now for the good news…if you have a fireplace, it makes those long winter days (and nights) a little more tolerable.

There are all kinds of options when it comes to fireplaces, but the one I really want to talk about is the oldest one known to many generations, the open hearth fireplace (one made with bricks, bricks & blocks or stones & blocks).  Nothing better at Christmas time! It’s particularly fun to watch the Christmas stockings that are hung by the fire with care in hopes that St. Nickolas would soon be there…but the real fun starts when you place bets on whose stocking gets sucked into the fire first because of the enormously strong draft of the fireplace.  The fun then stops when you go from your cozy and warm family room to how fast you can get into your jammies because your bedroom is now about 30 degrees!

The fact of the matter is, most open hearth fireplaces are extremely inefficient.  They are only at best about 7% to 10% efficient.  Efficiency goes from bad to worse with short duration fires, such as evening time only.  This is because the thermal mass (masonry) of the fireplace never has a chance to absorb heat and then radiate it back into the room.  Use of open hearth fireplaces can actually cause your heating bills to go up!

Other than poor efficiency, there are other problems as well.  If your furnace’s thermostat is located close to the room with the fire, of what heat is generated by the fireplace, will affect the thermostat.  This will result in the rest of the house being quite cold.  If it’s installed in an area of the home that is well away from the fireplace, the room with the fire will become too warm.  In other words, it becomes very hard to balance the temperature from room to room.  Of course, you also need to be wary of the fireplace that draws poorly.  A poor draft can result in indoor air pollution: smoke, soot, and even worse, carbon monoxide.  Poor draft is often the result of improper design from the firebox right up to the top of the chimney.

If you really want to use that old fireplace, first have it inspected.  You want to make sure the flue liners are in good condition and not cracked or missing.  An inspection by a professional will also check for creosote levels.  Excessive creosote is one of the main causes of chimney fires.  It forms when the chimney liner is cold and the fire is not burning efficiently or hot.  It really helps if you use dry or seasoned logs.  If you can hear it sizzling, the wood is way too wet.  The fire will not only burn poorly, but creosote will be produced much faster as well.

To help with efficiency, there are a few things to remember…when the fire is completely out, make sure the damper is closed.  Not only this, but make sure it fights tight.  You would be amazed at how much energy is lost when there is only a ¼” gap.  You might want to consider glass doors as well.  Glass doors will allow you to restrict much of the draw of the warm air out of your home while the fire is going out.  After consulting with a fireplace specialist, an air intake to the firebox will help as well.  A properly designed intact duct will reduce much of the air that was heated by your furnace from being used for combustion, and then up the chimney.

These few suggestions will help, but the best way to solve the problem is by having your fireplace expert install a sealed unit.  Examples of these can be found on the Lennox website: ….. Good luck this winter!

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