25 September 2024
Choosing the best firewood and caring for your fireplace
Firewood is a popular way to heat homes, outdoor spaces, as well as pubs and restaurants. From choosing the best firewood and storing it correctly to chimney safety, there is a lot to think about. These can all impact the efficiency, heat output, and creosote build-up in your chimney and flue. In this blog, we’ll explore the different types of wood available, storage, chimney safety, and how to keep your fireplace clean.
Types of firewood
Firewood can be categorised into 2 main groups; softwood and hardwood. Hardwoods tend to be denser than softwoods. This means hardwoods burn slower and produce more heat than softwoods.
Hardwood
Hardwoods come from angiosperm trees. Angiosperm trees are characterised by producing fruits that encase the seeds of the plant and they have broad leaves. They are usually deciduous meaning they drop their leaves in the autumn/winter time. Examples of hardwood are oak, ash, beech, and birch.
Softwood
Softwoods come from gymnosperm trees which tend to be evergreen and have seeds which are not encased in fruit. Examples of softwood are pine, cedar, and larch.
Choosing the best firewood
Seasoned vs Green wood
Seasoning wood refers to leaving the wood for around 12 months to dry out. During this process, the tree sap and internal water will evaporate making the wood more efficient for firewood use. Green wood is freshly cut from a living tree. It will still contain a high quantity of sap meaning it is not ideal at that stage for firewood use. Often when wood is referred to as ‘wet wood’ it means green wood. Some rainwater on the outside of the log will dry off quickly and doesn’t mean the log has been unseasoned.
Seasoned Vs Kiln Dried logs
Whether you are burning seasoned or kiln dried logs, your firewood must have an average moisture content of 20% or less. This ensures you get a consistent burn with more heat and little smoke. You can ensure a moisture content of 20% of less by looking for the Ready to Burn logo from your firewood supplier. There is more on the Ready to Burn initiative later on in this blog post.
Seasoned Logs
Seasoned logs rely on nature to dry. This means that the drying process is a lot longer than that of kiln-dried logs. Hot, dry summer days and crisp, frosty mornings are the best weather conditions for seasoning firewood. We season our logs in 10ft lengths for 12-14 months before cutting and splitting the lengths into logs. Once cut into logs of the desired length, they are further stored for around 6 weeks in boxes to allow the air to circulate and finish the drying process. This allows us to achieve a moisture content of 20% or under.
Wood left in long lengths to season.
Kiln Dried Logs
Kiln dried logs are force dried in a commercial kiln for a number of days, usually 7 to 10 days. This dries the logs to 20% or less. The carbon footprint of kiln dried logs is higher due to extra handling and wood & electricity needed to fuel the kilns. This also leads to kiln dried logs costing more than seasoned logs.
Which is better?
When choosing the best firewood for your fireplace, during the summer, autumn, and early winter, there isn’t an awful lot of difference between the two except the price! It is best to get seasoned logs delivered over the summer, as long as you store them correctly. The firewood will continue to dry out with good air circulation. If you don’t have much storage or need a mid-season top-up, kiln dried logs really come into their own at the end of winter and during spring when the weather has been more inclement. However, it’s good to consider that logs will always take in the ambient moisture so although you may buy kiln dried logs at 10% moisture, if ambient moisture is 18%, the logs will reabsorb moisture up to 18%.
Ready to burn initiative
Ready to Burn is a relatively new scheme. It was introduced to help reduce smoke and pollutants produced from burning, ensure firewood is legally sourced and gives consumers confidence in buying products, which can be burned straight away. The scheme is run by Woodsure who carry out regular checks on firewood businesses and test samples of logs to ensure they have an average moisture content of 20% or less. An average moisture content of 20% or under, ensures the logs burn hotter, producing less smoke and fewer emissions than wet wood. Woodsure distributes logos containing the business name and unique identifier to businesses that have passed the testing. An example of this logo is as below.
Ready to Burn Logo
Characteristics of Different Hardwoods
The 4 main firewoods used in the UK are oak, ash, beech, and birch. They are all hardwoods. This is because they are denser than the softwoods, meaning they provide a longer burn time but also have less resin and don’t spit as much as the softwoods. Softwood is great for kindling, to get the fire started but won’t give you the burn time that hardwood does. Below is a summary of each of the 4 main hardwoods:
Oak
Oak is one of the denser firewoods meaning it burns hot and for a long time. It is however difficult to light and best burnt alongside another firewood type. It is also a good option for people looking to smoke foods as it provides a unique flavour.
Ash
Ash produces good heat but is more difficult to burn than other hardwoods. There is currently a lot of ash firewood around due to a disease called ash dieback. The ash dieback is caused by a fungus which, if left, causes the tree to die.
Beech
Beech tends to be a good all-rounder. It provides good heat and reasonable burn time whilst also being easier to light than ash and oak.
Birch
Birch is often confused as being a softwood. This is because it shares some properties of softwood. It is a hardwood but it burns quicker than denser hardwoods. Due to its fast burn time, it is best mixed with a slower burner however some people do like to burn it alone.
The best species of firewood for you tends to come down to personal preference as well as what is best suited to your individual wood burner or fireplace.
Firewood storage
Seasoned or kiln-dried, firewood will always contain some moisture as well as reabsorb moisture from their surroundings. This means it is important that when storing your logs, they are stored in a well ventilated location.
How to store your firewood
The best storage solution for your firewood is a log store with one open side, three slatted sides, and a slanted roof. This will provide the logs with the best airflow and the slanted roof will ensure most of the rain stays off. The next best solution to a log store is stacking logs outside along a wall, covering the top with an unrolled roll of bin liners and leaving the front open. Covering both the top and sides of the logs is not recommended as this will trap moisture and cause the logs to sweat. It is best to stack logs on a pallet, if stacking alongside a wall, to keep them off the damp floor.
An example of our log store with 3 slatted sides and a slanted roof.
Where to store your firewood
When considering how to store your logs, it is also best to consider where to store your logs. Somewhere away from streams or water sources and in a breezy location is best to keep them dry. Any well seasoned firewood will reabsorb moisture from water sources if stored close enough. Garages and sheds are not suitable for log storage as there is inadequate airflow to ensure your logs remain at 20% or below. Because of our mild, damp winters storage with good airflow is vital.
If the logs happen to get rainwater on them, don’t worry! They will dry out quickly when placed out of the rain. Bringing the logs inside before lighting a fire will dry off any surface rainwater quickly but also can warm the logs up prior to burning, making them easier to light especially if it is very cold outside.
Chimney safety
It is important to get your chimney swept at least once a year, more if you use your fireplace often. This is important as the chimney sweep will be able to remove creosote deposits from the walls of your flue. Creosote builds up even when only burning hardwood.
What is creosote and how is it formed?
Creosote is a black tar-like substance which sticks to the walls of the flue. It is highly flammable which is why it is important to get your chimney swept regularly. Creosote forms when by-products from burning move up the flue and cool down. This causes them to condense and stick to the inside walls. In addition to being a fire hazard, when creosote builds up it reduces the diameter of the flue, reducing the draw on your fireplace. This makes it more difficult to light and maintain a fire, and you may find the initial smoke isn’t drawn away as well as usual. The weather can also affect the draw on the chimney, explaining why sometimes it can be more difficult to light a fire than other times.
What can cause increased creosote formation?
Increased creosote can arise from burning softwood, unseasoned wood, the characteristics of the chimney and flue, the way the appliance operates, or burning wood without enough airflow. This is why choosing the best firewood for your fireplace and looking for the ready to burn logo is important when buying firewood.
To reduce the formation of creosote, it is best to burn mainly hardwood. Burning with the air vents on the stove fully open when starting the fire can provide more airflow to start the fire faster. These air vents can be turned down once the fire has been initiated and is burning well but they should always remain partially open. Closing the air vents fully whilst burning can cause incomplete combustion, increasing the amount of creosote formed.
It is also a good idea to consider the size of the wood that you start the fire with. Starting the fire with kindling and smaller bits alongside logs will start the fire hotter faster than using logs alone. Getting the fire up to a steady burn quicker will also result in less creosote production.
A net of kindling to be used to help start the fire.
What does a chimney sweep do?
When the chimney sweep comes, they will initially conduct a visual inspection, which they can carry out by eye or with a digital camera. This can identify any blockages from creosote build-up, soot, or bird nests. They will then use extension poles with brushes attached to remove material from the lining of your chimney. The chimney sweep will vacuum up the removed material. Most chimney sweeps bring dust sheets to lay around the fireplace to ensure they keep the surroundings clean. If you need to find a chimney sweep a good place to look is on the HETAS website.
Keeping your fireplace clean
It is important that you regularly clean your fireplace, removing the leftover ash and cleaning the glass. It is always best to leave a little bit of ash in the bottom as this provides an insulation layer and makes lighting the next fire easier. Make sure the ash has fully cooled prior to cleaning, the ash bed can remain hot for a lot longer than the surface ash.
Uses for fireplace ash
Fireplace ash has a number of different uses. It is a great source of nutrients such as potassium and calcium which promotes flowering and the production of fruit. Adding ash to your garden soil raises the pH making the soil more alkaline. Plants which flourish in alkaline soil therefore can benefit from a dusting of ash. Not all plants thrive in alkaline soil though, so it is best to check before adding ash to your garden. Ash is also a great cleaning agent. It is slightly abrasive making it the perfect substance, when damp to clean the wood burner glass. You can watch how to do this here.
In conclusion, choosing the best firewood is important. It ensures you get optimum heat output whilst keeping creosote formation to a minimum. We always would recommend burning seasoned hardwood logs in your fire. However, the species of wood tends to come down to personal preference as well as what is best suited to your individual wood burner or fireplace. Storing your firewood correctly and in a suitable place to ensure it remains as dry as possible can really help keep your chimney clean. Despite this, the chimney sweep should visit at least once a year to keep the chimney free from blockages. It is important even if you don’t burn much as birds often find chimneys as suitable nesting locations