How to Raise the Efficiency of Your Fireplace

by Don Ames,


Story tells of a gentleman that came home from work and found his home was a little cool. Deciding to build a fire in the fireplace and not wanting to wait for the fire to get going, he looked to the charcoal lighter fluid that he often used. On this evening, the lighter fluid can was empty, so he went to the garage and looked for a substitute.

Finding a can of starting fluid that said "highly flammable", he returned to the fireplace and sprayed it on the logs. Big mistake, when he lit a match and approached the logs, there was a thunderous explosion. Blue flames shot out of the lower vents and scorched his socks and legs. Luckily, no permanent damage was done to himself or the house.

Moral of the story is - if you're messing around with fire, break out the fire proof socks!

Improving the Efficiency of Your Fireplace:

The best way to improve the efficiency of your fireplace is by improving your fire burning habits. ( Not to mention the method that you use to start the fire.) Some good habits include:

1.  Hot, blazing fires are more efficient because  the combustion of firewood and gases is more complete.

2.  With a hot fire, the surrounding material such as bricks and other masonry, radiate more heat more efficiently.

3.  Replace your raised grate with an good old fashioned andiron and increase combustion efficiency.

4.  Glass doors slow the flow of room air up the chimney, but also slow the radiation of heat to the room. Open the doors wide until the fire is going out and then close the doors.


P.S.  An American word, Andiron is a derivative of the Old French word andier, meaning iron. In England they are known as firedogs. Andirons today take us back to the time of our ancestors, when life was not as hurried. Before the advent of our modern electronic, hectic life, the family gathered around the hearth and contemplated as the fire softly reflected off the andirons.

Dampers and Glass Fronts:

Dampers are an essential part of a wood burning fireplace. Controlling the flow of air that is available to the fire is the only way to control the size of the fire besides adding or removing firewood.

Glass fronts or doors also help control the flow of air to the fire, but their main purpose is to close off the flow of air that is sucked up the chimney when there is no fire.

The problem with using dampers or glass doors as a way to increase fireplace efficiency is the fact that they are seldom in good condition. Dampers get rusty and warped - glass doors get worn and loose. All the glass doors that I see during my home energy audits are ready to fall out of the frames. To get a workable house air leakage calculation, the glass doors have to be taped off.

Tube & Fan System

1.  Once the fire is burning hot, adjust the damper to the smallest opening allowed with out spilling smoke back into the room.

2.  Shut the damper completely once the fire has gone out and the fireplace is not in use.

3.  Don't trust the effectiveness of the damper to close off the chimney. Years of use can warp, pit, and rust the damper. Install and use additional equipment to close off the chimney.

4.  Install tempered glass doors. Open the doors when using the fireplace, close when not in use. If your not going to use the fireplace for several months, use some additional equipment to seal the chimney.

Wood Burning Fireplace Inserts:

Installing a fireplace insert can increase the efficiency of your fireplace by a factor of five. This metal unit sits right in the front of the fireplace and turns the fireplace into a wood stove. The fireplace chimney is used for a chase and a new metal liner is placed inside. The insert has a heat ex-changer which warms and circulates the warm air and is the main reason the insert is so efficient.

The other big advantage is the opportunity to control the amount of air the combustion chamber has available. The front doors on the insert allows greater control of combustion air.

To get more efficient heat from your fireplace and still have the opportunity to see the fire and enjoy the fireplace atmosphere, a fireplace insert is the best way to go.

Another real advantage of the insert is the ability to keep using an old, unsafe fireplace. Older fireplaces with chimney's and firewalls that are no longer safe can be used again by installing a fireplace insert and chimney liner.

Tubular Inserts and blower Fans:

Tubular inserts that use a system of hollow metal tubes in the shape of a "C" are not effective unless they are used in conjunction with glass doors or blowers. They are designed to allow cooler air to enter the tube openings near the floor of the box, travel up through the tubes, taking on heat from the fire, and then entering the room at the top of the fireplace. By adding a fan to force the air through the tubes increases the effectiveness of this system.

The glass doors and damper are used to control the rate of burn and the fan speed is used to control the flow of air through the tubes.

Quality Fire Wood.

Cozy Fireplace

To assure the efficiency of your fireplace, the quality of the firewood must be considered. In each part of the country, you will have firewood available that comes from a number of different species of trees. One species may burn hotter and another may burn with more smoke and unwanted gases. One species maybe easier to start but burn quickly and make it difficult to hold a fire over night.

Firewood research is particularly important as some species of wood when burned in a fireplace leave large amounts of residue behind that can line the inside of the chimney and increase the chance of having a chimney fire. Hardwood, such as Oak, often makes the best firewood because Oak burns, hot, slow, and clean.

Burning dry firewood is also important to get the most efficiency out of your fireplace. Firewood can be wet in two ways. One way is the result of rain and the other is the result of being cut recently and wet with sap.

The best firewood is cut a year in advance. This allows the firewood to dry from the inside out and not be wet with the sap and moisture it contained when it was a part of a living tree. This type of "wet" is the most important when evaluating firewood.

The other type of wet firewood is the result of being rained on after it is stacked outside and waiting to be burned. This type of moisture is usually not a problem and will dry quickly once placed in the firebox.

The secret to a high efficiency fireplace then comes down to three items:

A.  The first being household habits. Operating the fireplace with efficient habits in mind and knowledge of what creates inefficiency.

B.  The second item is equipment. The type of fireplace equipment you have and how well it is maintained.

C.  The third item that greatly effects fireplace efficiency is the quality of the firewood. A good dry stick of hardwood is hard to beat.

Thanks for stopping by Detect Energy, Hope you'll come back soon, but I won't leave the light on for you...

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Tags: a, burning, efficient, energy, fireplace, is, loser, wood


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Comment by Jeena Smith on May 10, 2013 at 1:43am

Hi Don,

Thanks for discussing these above tips, and i do agree with all your suggestions.Let me tell you one fact, that in a recent survey on fireplaces it has been found that the efficiency of your fireplace is 70% depends on the quality of inserts which you use for it.

So, i guess more importance should be given to this, right?

Some nice fireplaces suggestions: Fireplaces
Comment by Don Ames on January 15, 2012 at 12:27am

Bob,  I only see one picture with your comment, looks like the flue damper to me. The lever on the side might have to do with combustion air. I hope someone else jumps in here and can help us out. Also, if you would like to contact me at, perhaps you could send mire pictures and we could figure this lever business out.  Don Ames

Comment by Bob Blanchette on January 14, 2012 at 11:32pm

Our house was built in 2000 with a metal fireplace surrounded by cosmetic brick. I would like to know how to prevent air from leaking and what that side lever is for. The last photo shows the damper/flue, it may give you a better idea of brand/model/type of fireplace this is.

Comment by Don Ames on November 10, 2011 at 1:47pm

Your welcome Marie, Thank you for compliment, much appreciated.  Don Ames

Comment by Marie McMahon Meehan on November 10, 2011 at 1:34pm

Great article, Thanks!


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