Extra firewood tips
As a firewood user you may have been using firewood for many years and have gained, through experience, the knowledge to know what is good quality firewood, or this may be your first ever purchase of firewood. Whatever the case, we hope that the following page is of some use as a guide to buying good quality firewood.
Quality is not just about the product, it is all encompassing, it should cover the whole firewood purchasing process form ease of ordering through to efficient delivery suitable to your needs.
Whether your fire or stove is providing all the heat and hot water for the house, or you’re only using it to give a nice atmosphere to a room, remember that burning wood will provide reliable, environmentally friendly, sustainable and cheap heat. Therefore what you’re actually paying for when you buy firewood is heat, so when buying firewood you shouldn’t be thinking in terms of – do I go for pine or oak, seasoned or unseasoned? You should be thinking – How much heat am I getting?
THE IMPORTANCE OF BURNING DRY WOOD
· You get far more heat from the same amount of timber.
· You get higher temperatures in the grate, and wood, unlike coal, needs these high temperatures to bun efficiently, this is very important.
· Fire stays alight better and is far more controllable especially on modern stoves.
· Far less build up of waste substances in the fire, flue and chimney and hence fewer of the problems associated with this.
Fresh felled wood is very wet
When a tree is cut down, the timber can be very wet or “green” – 65% water in some cases. The firewood should be properly dried or “seasoned” before it is burned.
Burning wood which is not dry…
· Causes tar and other waste substances to build up in the fire and the flue, which can lead to chimney fires and chimney corrosion.
· Is inefficient – all the fire’s energy goes into boiling water out of the log rather than putting heat into the room.
· Doesn’t produce as much heat. Wet logs smoulder, produce smoke and steam and don’t produce many flames or burn well.
· Shortens the life of your boiler if you have a stove fitted with one.
· Can be extremely damaging when mixed with coal type fuels. Much of the coal, and smokeless fuels has a high sulphur content. When water vapour from wood combines with sulphur, you are likely to form sulphurous acid on to any cold surfaces within your system.
If this is the first time you have ever bought firewood, then it would be a good idea to do a bit of research or at least give a bit of thought to what will work well in your particular stove or fire.
If you have recently bought a stove or fireplace they often come with an information leaflet describing the best fuels, including information on species and size of logs. The size of logs is important as it affects how much wood you will be able to fit into the grate and hence affect the overall heat output. Good suppliers will be able to supply logs in various lengths, which should be close to what you require.
A NOTE ON SOME STOVE MANUFACTURERS RECOMMENDATIONS: In some cases the specification that comes with stoves is a little unrealistic, stating such things as “Oak, Ash and Beech seasoned for 3-4 years”. If you were to ask most firewood suppliers for this it is unlikely that they could supply it. The length of seasoning is not as relevant as the actual moisture content of the wood, also by limiting yourself to certain species you will limit the availability of supply. See the rest of this information for more details of what is a good idea to burn.
WHAT TYPES OF WOOD BURN BEST?
You may or may not have heard various rhymes which impart information on good and bad types of firewood. Whilst these rhymes are very useful, one aspect they commonly refer to is the ability of certain species such as Ash, Holly and Birch being good to burn “green” / unseasoned / wet. Whilst these species are capable of burning green unlike most other types, they still have the same problems of any wet wood – less heat, lower efficiency and more tar. Therefore it is better burn any species when dry.
When firewood is dry, there is almost no difference in heat output between hard and soft woods by weight. The main difference between hardwoods and softwoods is the volume of the wood you will need to burn. Dry softwood logs provide a good flame and burn well, but burn more quickly than a hardwood log of the same volume.
The weight of softwood is around 50% bulkier in volume than the same weight of hardwood, so to obtain the same heat output from softwood logs as from hardwood logs you will need to use 1.5 times more volume.
However, an open fire has a few differences which make some types of wood less suitable. Open fires have lower temperatures in the grate, and therefore have lower efficiency resulting in more tar being produced. Therefore softwoods, which have more resin, are less suited to open fires. Also any type of wood which has a tendency to spit such as Sweet Chestnut, Larch and to a lesser extent the other softwoods, will be inappropriate for open fires as they may send hot cinders out into the room.
Good suppliers will be able to tell you what types of wood you can expect to be delivered in the load.
SEASONED OR UNSEASONED?
What should be meant by “seasoned” is dry enough to burn well, however there is some ambiguity over how dry is seasoned wood. Some people think that if wood is left outside for a year then that is seasoned. As far as you, as a customer, are concerned then what you want to be putting on your fire is wood that is around 20-25% moisture content or less. Some suppliers have moisture meters some don’t, but they should all be aware of the approximate moisture content of their firewood.
If you are lucky enough to have plenty of good, dry but well ventilated storage, then you have the option of buying unseasoned firewood and storing it yourself for a year or so until it’s ready to burn. This has the advantage that you control the seasoning process and can reduce the moisture content to your desired level, this may take over a year for some species. Also unseasoned firewood is often cheaper than seasoned.
If you want your firewood delivered ‘ready to burn’, stress to your supplier that the wood must be well seasoned. A good sign that logs are well seasoned is that the end grain will have quite a few cracks (see the photo) – these cracks are a result of the wood shrinking as it’s dried.
WEIGHT OR VOLUME?
A lot of suppliers deliver by the “Load”. But what is a load? It can vary from a small box trailer through to the back of a tipping transit van, this can lead to confusion for you as a customer when trying to compare suppliers for value for money. What is more useful is the actual quantity of wood, most suppliers will give you the approximate weight of their load or even the volume. If you’re trying to compare value for money you need to remember that the weight is very dependent on how wet the wood is, whereas the volume does not change with moisture content, therefore when buying by volume you’re not paying for water.
It is important to find out from your supplier how they deliver the firewood, if you live in a terrace with no front garden and only a narrow alley to access the back yard, then you won’t want a tipped delivery, you’ll need to have a delivery method which can be loaded onto a trolley of some kind. Below are listed some option for delivery with their pros and cons. However not all supplier use all of these so you will need to check if your chosen supplier can deliver with your preferred method.
· Tipped delivery; Fast, cheap, common to most suppliers so you are not limiting your supply base and can delivery large quantities. Large amount of manual handling for you as a customer to move it to your wood store (unless you have a large enough wood store with good access to allow the load to be tipped directly into it), need good vehicular access.
· Tipped delivery with a stacking service; (The supplier will stack the firewood into your store) No manual handling for you as a customer, can deliver large quantities. Not offered by many suppliers, usually an extra charge.
· Dumpy bags; Cheap, quite fast, doesn’t need as much delivery space as a tipped delivery, can be used as a store if covered correctly. If not using the bag as a store there is a large amount of manual handling for you as a customer to load it into the wood store.
· Barrow bags on a trolley; Cheap, allows access to restricted spaces, can get very close to wood store. Fairly slow for any quantity.
· Potato crate; Quite fast, doesn’t need as much delivery space as a tipped delivery, can be used as a store if covered correctly. If not using the crate as a store there is a large amount of manual handling for you as a customer to load it into the wood store, you may have to pay a deposit on the crate as they are expensive.
· Steel cages; Quite fast, doesn’t need as much delivery space as a tipped delivery, can be used as a store if covered correctly. If not using the cage as a store there is a large amount of manual handling for you as a customer to load it into the wood store, you may have to pay a deposit on the cage again you may need to pay a deposit on the cage.
· Net bags; A common packaging method, convenient for occasional users. A large amount manual handling and also usually an expensive option.
AND MOST IMPORTANTLY, PRICE!
Possibly one of the biggest variables when buying firewood today is the price, prices from £40 up to £200 can be quoted for a “load”, but as stated previously not all loads are the same. Remember, what you’re handing over the cash for is heat, therefore to compare suppliers ideally you need to compare the amount of heat they’ll be delivering, normally measured in units of kilowatt hours (kWh, the same as your electricity or mains gas bill), this also enables you to compare it to your fossil fuel heating – and you may well find it significantly cheaper! But working this out is not necessarily straightforward, you need to factor in the volume or weight delivered and the moisture content of the wood, which is not something that most people want to be doing every time they order firewood. At present there aren’t many suppliers which can give you the approximate heat value (sometimes referred to as the calorific value) of the load you’ll be getting, however one of the aims of the project is to train suppliers to enable them to carry out these types of calculations in order to inform you the customer better.
In the meantime here are some figures on the range of prices for various types of firewood. Also what that price approximately equates to in kWh – this does not take into account the efficiency of the appliance you are using to burn it on (but neither does your gas or oil price);
· Seasoned hardwood (less than 25% mc);
o £175 – £230 a tonne
o £60 – £80 per loose cubic metre (piled not stacked)
o 4.7p/kWh – 6.2p/kWh (if burning it straight away)
· Seasoned softwood (less than 25% mc)
o £150 – £200 a tonne
o £35 – £45 per loose cubic metre (piled not stacked)
o 4.3p/kWh – 5.6p/kWh (if burning it straight away)
· Unseasoned hardwood (~50% mc)
o £120 – £160 a tonne
o £60 – £80 per loose cubic metre (piled not stacked)
o 5.2p/kWh – 6.9p/kWh (if burning it straight away, this is theoretical as wet wood will not burn efficiently therefore taking this cost far higher)
· Unseasoned softwood (~50% mc)
o £105 – £135 a tonne
o £35 – £45 per loose cubic metre (piled not stacked)
o 4.9p/kWh – 6.2p/kWh (if burning it straight away, this is theoretical as wet wood will not burn efficiently therefore taking this cost far higher)