When sitting near a wood burning fireplace, it can seem that the fire isn’t producing that much heat. In fact, the majority of the heat from a wood burning fireplace can be lost up the chimney, rather than making its way into your home.
Fireplaces are a great focal point for any room, but their ability to transfer heat into your home can be less than optimal if not used efficiently. There is a range of variables can that dictate how much heat a fire in your fireplace can provide.
So what can you do to get more heat from your open fireplace?
I’ve spent years trying to perfect the amount of heat I can draw from the wood burning fireplace in my living room, and so I’ve put together the best ways on how to get more heat from your open fireplace.
Use Dry & Well Seasoned Logs
Well seasoned or kiln dried logs should be used as they typically come with lower moisture contents. Don’t use wood that has been recently cut or looks greenish in color.
Seasoned logs are pieces of wood that have been left to dry to allow the moisture to evaporate from them. When cut, wood has a moisture content of around 60%, which is too much to efficiently burn in a wood burning fireplace. Wood with such a high moisture content will be hard to light, will lead to lots of smoke coming from the fire and won’t produce that much heat.
A moisture content of 20% or less is usually recommended for use in a fireplace, as wood with higher moisture content than 20% starts to become harder to burn, and gives off more smoke as a result.
Therefore use well seasoned or kiln dried wood with a moisture content of 20% or less to get the most heat from the wood that you’re burning.
More energy will be required to burn off excess moisture from the wood, meaning that it will produce less heat overall.
If you’re using wet wood, you’ll probably hear hissing noises coming from the fire as the moisture is burnt off. Sufficiently dry wood makes a hollow sound when banged together, may start to have cracks in the end, and any bark may be starting to come away.
You can also use a moisture meter to quickly find the moisture content of your logs.
Use Hardwood Logs Over Softwood
Burn hardwoods to get the most heat over the course of the fire. Burn softwoods to get hotter but shorter lasting flames.
Hardwoods are denser than softwoods and so burn slower than softwoods, meaning that you’ll use less wood over the course of the fire and get more heat out of every piece used.
Softwoods also contain more sap than hardwoods. Burning softwood releases more soot and other particles and can buildup on the inside of your chimney.
Hardwood comes from deciduous trees (tress that lose their leaves over winter) and softwood comes from evergreen tress (tress that keep their leaves all year round).
Hardwood includes Oak, Ash, Beech and Douglas Fir, while softwoods include Cedar and Pine.
Hardwoods take longer to grow, take longer to dry and are harder to light, but burn the longest and can produce the most heat over the course of every piece.
Softwoods are quicker to grow, quicker to dry and easier to light, but burn much more quickly than hardwoods.
Douglas Fir is well known as the hardwood that provides the most while also lasting in the fire for a reasonable amount of time
As hardwoods take longer to dry out than softwoods, you’ll need to pay extra for the privilege of using hardwood in your fireplace.
Whichever wood you choose, be sure to only use wood that is dry.
Softwoods should ideally be used at the start of a fire to help it get hot quickly. Once a layer of hot ash has been provided within the fireplace, hardwoods can then be used to keep the fire burning for longer and hotter.
Get Your Chimney Swept
A clean chimney means a greater draw for your fireplace.
Using your fireplace will cause soot and other particles will buildup on the inside of our chimney over time. This buildup of soot will reduce the overall diameter of the chimney, which in turn will reduce it ability to draw air from the fireplace.
Less suction for air up the chimney will also reduce the airflow to the fire.
Creosote is also released through burning wood and can line the walls of your chimney. Creosote is a flammable substance that can lead to chimney fires if not removed.
I get my fireplace swept every year before winter in line with official recommendations. If you regularly burn softwoods such as Pine in your fireplace then your chimney should swept more often than once per year.
You can read more about how often your chimney needs sweeping and why.
To help increase the heat output of your fireplace, you should get your chimney swept at least once per year, ideally before the winter season.
A clean chimney will help maximize the potential draw of the fireplace, feeding more air to the fire and increasing the heat output from the fireplace.
Fully Open the Damper
Check the damper in your fireplace to make sure that it’s wide open to allow for maximum draw of air up the chimney, which in turn will increase the airflow to the fire.
A damper is usually shut between fires to prevent the loss of warm air from your home.
If you have a damper it will either be located just inside the top of the fireplace (at the base of the chimney), or located at the top of the chimney and you will have a pull lead in the fireplace to open it.
With the damper fully open your wood will burn hotter and faster thanks to increased airflow.
A wide open damper will increase the combustion rate of your wood, meaning that you will burn through wood quicker than usual. If you’re wanting to get the most heat out of your fireplace then you may have to sacrifice the longevity of the wood that you’re using.
An open damper will also ensure than any smoke or harmful gases created by the fire will escape up the chimney, and not into your home.
If, like myself, you don’t have a damper in your fireplace, then there’s no need to worry about having to open a damper before starting a fire.
You can also learn how to use your damper to control the rate at which the fire burns by partially opening and closing the damper.
Ventilate The Room
Providing ventilation to the room in which your fireplace is located may be just as important as keeping your damper open and your chimney clean.
A chimney is designed to draw the air out of the fireplace and out of your home. The air lost from the fireplace needs to be replaced, and if there’s a lack of ventilation within the room then a vacuum can be created. This vacuum can lead to a reduction in the ability for the chimney to draw air from your fireplace, and therefore fresh air into the fire.
Many new homes are tightly built, with little room for air to make it’s way into the house. This can cause air supply issues for a fireplace.
To help improve the heat output of your wood burning fireplace, sufficient ventilation within the room should be provided to allow for a constant supply of fresh air to the fire.
Leaving doors to the other areas of the house open, or even leaving a window in the room slightly open can help improve with airflow to the fireplace. The window doesn’t have to be wide open; a few centimeters will suffice.
If you have a vent in the room like we do shown below, be sure to have it wide open throughout the duration of the fire. Ventilation from the outside of your home through a vent or window can help prevent the warm air in your home being sucked out through the chimney, instead of fresh air from the outside.
Start The Fire Properly
In order to improve the heat output of your wood burning fireplace, you’ll need to get the fire off to a good start. This involves setting up the fireplace properly to maximize how quickly the fire catches on.
Start with laying a few crumpled bits of newspaper (but not too tightly packed) in the fireplace, and a few bits of dry kindling on top. You can then finish of the fire by adding small logs on top of the kindling.
Don’t start the fire with large pieces of wood
You’ll want to provide sufficient spacing between the wood to allow for airflow. Be sure not too leave too big of a gap otherwise the heat won’t transfer between the wood and the fire will burn more slowly.
Leave the fire to get going, allowing the chimney to warm up before adding any more wood.
As the fire and coals start to warm up you can start add logs that are bigger in size.
Keep The Fire Going
After setting up and starting the fire you’ll need to keep the fire going strongly if you want to get the most heat out of your fireplace.
Kindling and small bits of wood should be used when starting the fire. Once the fire is going and a bed of hot coals has started to form, you can move onto using larger pieces of wood. Hardwoods will now be a good substitute for softwoods as they will burn and for longer and provide more heat over the duration of the fire.
The way in which you load the logs can also play an important role in how much heat can be produced by the fire.
Laying smaller bits of wood evenly spaced out in your fireplace in a crisscross pattern will help with airflow, and increase the rate at which the wood is combusted. This will create a hotter fire, but the wood will burn more quickly as a result.
Placing larger pieces of wood in your fireplace more closely and densely together will keep the fire going for a longer period of time between each refill, and will provide the most heat output per piece of wood.
Don’t wait until the fire is smoldering to add further logs to the fireplace. A flame should be visible at all times. Both the flames and the hot coals from the fire will ignite the new bits of wood and keep your fire burning.
Keeping an eye on the fire and understanding how it’s behaving will help you judge how best to get the most heat from your fireplace.
If see you smoke coming from your fire, it can be a cause for concern. Smoke can be produced from the fire when the wood isn’t being burnt properly. This could be down to using wood that is too wet, or when there isn’t enough air flow to the fire, commonly caused by a closed off damper of partially blocked chimney.
Maintain The Fireplace
Periodically cleaning and maintaining your fireplace will help to maximize airflow, while also providing a bed of ash to help improve the heat output from your next fire.
The ash in a fireplace shouldn’t be completely cleaned out, although it should be kept on top of to help with getting airflow to your fire. Periodically remove small amounts of ash to keep the level of ash in your fireplace to a maximum.
Between one and two inches of should be kept within your fireplace at all times. The ash will help insulate the new bed of hot coals in the next fire and help to improve its heat output.
A layer of ash will help with the combustion of the wood, and you may find it more difficult to get a fire really going if all of the ashes have been cleaned out.
Install A Fireback
As the name suggests, a fireback goes at the back of the fireplace behind the fire.
A fireback helps reflect heat off the back and sides of your fireplace and out into your room. This heat would have otherwise been lost into your firebox surround or up the chimney.
A fireback also works much like a wood stove works and absorbs the heat from the fire, radiating the heat out even after the fire has subsided. This helps give you that extra warmth that couldn’t be provided by a finished fire.
A fireback is essentially a sheet of metal that is usually made of the same material as a wood stove; cast iron or steel to help radiate the heat into your room.
How To Get The Most Heat From A Fireplace
There’s a few things you can do to instantly improve the amount of heat you can get from your open wood burning fireplace, including using hardwoods over softwoods, using woods that are of low moisture content, getting the fire going properly and maintaining the fire over the course of the cycle.
Also be sure to have your chimney swept if you haven’t done so in the last year.
You can’t expect to be able to get the maximum amount of heat from your fireplace on the first try. Every fireplace is different and there are a number of different variables that can all play a role in how well a fireplace works. These can include the size of the firebox and chimney, the amount of ventilation within your house, and temperature difference between the inside and outside of your home.
By following the advice above you can learn to understand how your fireplace works the most efficiently, and use it to its maximum potential for providing the most heat output into your home. If you have tried and tested the above ways to help increase the heat from your fireplace but still want more heat, you will probably need to start looking at other forms of fireplace, such as a wood burning stove. A stove will vastly improve the heat output from burning your wood in your home, but at the downside of a large upfront cost and the loss of having an open fire.