Don't let your woodpile go up in smoke. Here's how to increase the efficiency of your fireplace or wood stove with maintenance, wood choice and more.
Ways To Increase the Heat From Your Wood-Burning Fireplace
Published on Dec. 03, 2024
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What Might Cause a Fireplace to Burn Low?
Fire needs ample fuel and oxygen to thrive. So if your fireplace is burning low, it’s not receiving enough of at least one of those. Common factors causing that are wet wood, a clogged chimney or vents that are closed too far.
“If a fireplace burns low occasionally and you didn’t experiment with woods, the cause is most likely a clogged chimney or flue that restricts airflow,” says Jon Gilbertson, president of Chris Heating & Cooling. “If your fireplace started burning low after you switched to another wood, then the new wood is likely wet or unseasoned, and too much moisture doesn’t allow the fire to reach optimal heat levels.”
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Burn Better Wood
“The number one way to increase heat output is to use better wood,” says Dan Morris, founder of Fire and Saw. So don’t just grab any old log. Rotting wood and freshly cut wood won’t burn well. Also, hardwoods, like oak and hickory, burn cleaner than soft woods like pine, since they have less sap (though it is easier to get a fire started with a bit of soft wood kindling).
“And specifically wood with a high BTU will burn hotter,” says Jeff Waldman, a builder and designer with Elevated Spaces. “A hot fire is a good fire, as it creates a lot of airflow and burns off smoke and resin, reducing the buildup of creosote in the chimney and stove.”
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Season Your Wood
Once a tree is cut down, its wood needs to be dried out, or seasoned, before it will make a good fire. That process takes at least a few months up to a couple of years depending on the wood and your location. “Essentially we don’t want the stoves to be spending energy drying the wood out prior to burning it, which makes it inefficient for heating,” says Cory Cameron, a fireplace exert at Fireplaces By Cameron.
Wood should generally have between 10% and 20% moisture, which you can check with a moisture meter.
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Let it Rest Inside
Even once wood is seasoned, it’s helpful to bring it inside for a week or so before burning it, says Cameron. “If you’ve got space and a nice rack to place it on, that’s going to bring the moisture content in the wood right down,” he says. “Benefits here are longer, more efficient burns, less creosote build up and you don’t have to keep lugging heaps of wood into your house every day.”
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Try Alternate Fuels
Gilbertson recommends compressed wood bricks, which are made from sawdust and other wood byproducts. “Compressed wood bricks burn hotter and longer than traditional firewood due to their uniform density and low moisture content, providing a more efficient and higher-heat output,” he says.
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Control the Airflow
Ample oxygen is vital for wood to burn well. If you’re using a manufactured fireplace or wood stove, check the manual for how to properly manage its air vents. “You’ll want a lot of airflow when first getting the fire going, then once there are good coals and a hot fire you can tamp it down,” says Waldman.
Tamping it down is important because running it wide open for long periods, aka overfiring, can damage your stove and waste wood. Waldman recommends mounting a thermometer to your flue so you can keep the temperature in the 250 to 250F range.
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Coals Are Your Goal
“You want to build a coal base, which generates heat and drives it upward,” says Leroy Hite, founder of Cutting Edge Firewood.
To make your fireplace burn hotter, he recommends starting the fire with small pieces, then adding pieces at least an inch thick as it gets going. These make coals that put off a lot of heat. Adding even larger pieces after that increases the coal base and the heat output.
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Use A Fan
Another way to make your fireplace burn hotter is to use a heat-powered fan. “These fans sit on top of your wood stove and push hot air, powered by heat, through your home,” says Morris. “We use one of these in our home and have found it surprisingly effective.”
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Arrange Wood Smartly
Start with small kindling, then gradually feed the fire with wood of larger diameters until you’ve worked your way up to full-size pieces. “If you just stuff some newspaper around a log, you’re likely to not build up enough heat to ignite a large piece of wood,” says Waldman. “And if you do manage to burn it, it’ll smolder and suffocate, producing low heat, poor flame and a smoke fire which builds up creosote in the chimney.”
Another option for arranging wood in a fireplace is log cabin style. Put two or three logs down as a foundation. Then place two or three more logs on top of those in a crisscross manner. “This allows for plenty of oxygen for the wood to burn,” says Hite. “The more oxygen the fire has, the hotter it burns.”
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Light it Properly
Often fires fail to create enough heat because they never quite get going, says Matthews. To avoid this in your fireplace or wood stove, her advice is to:
- Clean your stove while it is cold.
- Open the air vents fully.
- Light a sheet of newspaper inside the stove to heat the flue and move any air pockets that have gathered.
- Scrunch a few sheets of newspaper into balls and place them in the stoves.
- Crisscross 8 to 10 pieces of kindling in a lattice effect over the newspaper.
- Push more scrunched-up newspaper in the gaps between the sticks.
- If you’re using firelighters, add these on top of the newspaper.
- Light your wood stove.
- Leave the vents open and the door ajar.
- When the kindling starts to char, add two or three logs to the stove.
- When the logs start to burn, close the door properly.
- Partially close the vents, experimenting to see how far you can close them before the fire starts to smoke or smolder.
“Not crowding logs together and adding smaller pieces of wood can also help to maintain a high flame,” says Emma Bell, manager of Fires2u.
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Rotate the Wood
Periodically exposing fresh sides of the wood to the fire will encourage it to burn with more fervor and make your fireplace burn hotter. Use a poker to rotate logs, being careful to leave some space between them so enough oxygen can get through.
“If you’re using leftover logs from previous fires, make sure to rotate your wood,” says Gilbertson. “Use older logs first to ensure they burn efficiently, and keep newer or wetter logs for later when they have more time to dry out.”
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Tamp it Down to Maintain Efficiency
As well as being bad for your stove, operating at the highest temperature isn’t necessarily the best way to generate reliable heat either, says Matthews.
“Intense fires lose a lot of the heat generated straight up the chimney,” she says. “It’s better to have a less intense flame that will help your fuel to last longer and keep flammable gases inside the stove for longer so they can burn and generate more heat.”
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Buy a Fire Back
A deflector, or fire back, is a cast iron upright standalone plate in the back of your fireplace. It deflects heat outward while protecting the back of the fireplace. “Adding a fire back to your fireplace is an easy way to increase heat output 20% to 25%,” says Hite.
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Install Wood Stoves Properly
Wood stoves in particular need space to breath, in order to deliver maximum heat, says the team at ESSE wood-burning heating and cooking stoves. “By this, I mean do not enclose the stove in such a small space,” they say. “The more space the stove has around all sides and around the flue, the better heat it will deliver; and the longer flue length exposed will also give significant heat.”
Also, if your fireplace or wood stove is too small for the space you need to heat, you will always face an uphill struggle, says Matthews. “Use a stove size calculator to see the appropriate stove heat output for your room,” she says.
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Use Andirons or A Grate
It can help greatly to have logs lifted off of the bottom, which helps with airflow. Hite recommends andirons over grates in open fireplaces as they promote more airflow.
“Grates are more traditional than useful,” says Hite. “In the past, the English cut down almost all of their trees and therefore used charcoal or coal instead of wood in their fireplaces. Grates hold charcoal better than andirons, and so we inherited grates from the English.”
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Upgrade Your Fireplace
There are many fireplace insert designs. The idea is, the fire heats tubes in the fireplace, and the tubes return heat to the room. “Those are phenomenal,” says Hite. “Inserts are a way to increase the heat from your fireplace.”
You can also add a hearth pad beneath your fireplace and install a brick wall, which help you to enjoy the heat coming from the fireplace for longer, says Gilbertson. “These materials absorb heat from the fireplace and then gradually release it into the room, providing warmth even after the wood has burned out,” he says.
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Cool It With Cleaning
When you clean out your fireplace or stove, leave some ashes. “Cleaning does not increase heat output,” says Hite. “Also, a little ash in the bottom of the fireplace protects it from heat.” Here are several other ways to use fireplace ash.
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Keep It Serviced
Make sure to get your chimney cleaned once a year to avoid a chimney fire from the creosote (a tar-like substance) that accumulates there. “Cleaning will also keep things burning hotter and cleaner,” says Waldman.
Also, worn door and glass seals can cause over combustion, says the ESSE team, so annual stove servicing is also recommended.
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Use a Yule Log
When enjoying an evening fire, be sure to keep the damper open even after you’ve gone to bed. If it’s closed, you risk a buildup of carbon monoxide. Of course, this also means you’ll lose some furnace heat as well.
Hite has a solution: “You can put a big Yule log on the fire if your coal base is thick and will be hot enough to keep a big log burning and producing enough heat to offset the heat lost up the chimney,” he says.
The Yule log, BTW, was originally an entire tree. Families would bring the trunk of the Yule tree inside and piece-by-piece feed the fire through the Twelve Days of Christmas.
FAQ
What’s the best wood to burn in a fireplace?
Most fireplace manufacturers recommend seasoned hardwood, like oak, beech and ash, with a moisture content between 10% and 20%. However, Gilbertson also recommends experimenting with compressed wood bricks, because they are low on moisture and burn hotter and longer than many woods.
“Compared to wood logs, wood bricks produce less smoke and reduce creosote buildup in the chimney, are easy to carry home and store and are eco-friendly,” he says. “The only thing you’re missing when switching from wood logs to bricks is the scent of burning wood, since bricks just don’t give off that aroma.”
How hot can a wood fireplace burn?
“Hotter than you want it to!” says Waldman. Some stoves can reach up to 2,000 degrees F, but you should keep your flue temperature in the 250 to 450F range. Matthews says the ideal temperature for inside your stove is in the 500 to 860 degree range. “Using your stove at higher temperatures than this risks damaging the stove’s body and internal parts,” she says.
About the Experts
- Jeff Waldman is a builder, designer and writer who shares his projects, blueprints and experiences via his website Elevated Spaces and his newsletter. He wrote a book about tools, prefers building up in the trees whenever possible and lives in San Francisco.
- Dan Morris founded FireandSaw.com, where he shares expert insights on everything firewood, wood stoves and chainsaws.
- Christine Matthews is a spokesperson for Gr8Fires, a heating appliance retailer that has been selling wood stoves for more than 30 years.
- Jon Gilbertson is president and CEO at Chris Heating & Cooling, a family-owned company based in Chicago, where he began his career as a technician.
- Cory Cameron is a fireplace exert at Fireplaces By Cameron, which is based in Courtenay, British Columbia. He uses a wood stove as the primary heat source for his family’s 2,500-square-foot house.
- Emma Bell is manager of Fires2u, a family business established in 1981. She has over 17 years of experience selling gas, electric and wood burning fire places.
- ESSE wood-burning heating and cooking stoves have been manufactured in Britain since 1854 and was one of the first companies to introduce closed stove efficient heating designs to the UK.
- Leroy Hite is CEO and founder of Cutting Edge Firewood in Peachtree Corners, Georgia.
