Buying Firewood

BRIQUETTESCustomers need to have their wits about them when buying wood!

Some sellers will advertise "a tonne bag of logs", meaning the bulk bags used in the building trade to deliver one tonne of sand or aggregates to site. These bags are great, but bear in mind that you'll never get anywhere near a tonne of logs in one. It's best to avoid buying logs by weight, as this encourages people to sell wet wood which is of course considerably heavier than well dried stuff - you can get water out of the tap much more cheaply! (Briquettes on the other hand are almost always sold by weight as they are consistently a very dry product - much drier than natural logs)


Is that a cubic meter of actual wood, or a cubic meter of loose logs? A cubic meter of solid wood will make a lot more than a cubic meter once split into logs and chucked in a pile or in a bag.

Many people think that your common or garden builders bulk bag is a cubic meter. Very few of them actually are! Although they don't look a lot different in size, the difference in actual volume can be quite surprising. A bag 1 meter x 1 meter x 1 meter contains one cubic meter. A bag 90cm x 90cm x 90cm looks almost identical and yet only contains 0.72 cubic meters. If you have 70x70x70cm bags, which still look pretty big, then surprisingly you only have 0.34 cubic meters - a BIG difference if you're paying for what you think is a cubic meter!! If in doubt - tape measure out!

Can the supplier give you moisture readings on their firewood? Moisture readings should be taken on a freshly split log on the split face, not on what was the "outside" Seasoned is generally taken as a moisture level of 25% or below. Freshly cut timber can be up to 60% moisture! Naturally air dried wood in the UK is never likely to get much below 20 - 25% moisture due to the dampness of the air. Kiln dried firewood is expensive but obviously somewhat drier, though if stored outside it will gradually re-absorb moisture from the air which is damper than the wood. Generally speaking, the drier a wood is, the more heat it will give off for a given amount.

If the wood is well seasoned, most species will give satisfactory results. Some, like chestnut tend to spit and spark, and so should not be used on open fires. Birch burns hot, but doesn't last long. Elm, according to an old firewood poem, "burns like churchyard mold, e'en the very flames are cold" Ignore the poem! Most elm that gets sold as firewood nowadays is from dead trees, and if it's dry it's an excellent fuel.

Some UK companies are importing and selling African hardwood logs. We have mixed feelings on these to be honest. Some are being sold at source to provide funds for various charity and wildlife organisations, which is perhaps a good thing. It could also be argued that it is providing an income to a few third world families. However, a lot of people are attracted to wood fuels in the first place because they are classed as carbon neutral and therefore a "greener option" than fossil fuels. Transporting loads of firewood all the way from Africa however does not strike us as such a green option, and on balance we feel that this "fancy firewood" is not such a hot idea. The very high price is also likely to limit it's appeal to that section of society who think their friends will be impressed when they tell them they have their firewood specially imported. We personally feel that this firewood may be better used back in Africa by the families who produce it.

These are a relatively recent product and are made from sawdust and wood shavings from manufacturing that would have had to be sent to landfill once upon a time. They have a number of advantages over "normal" firewood:

  • Very low moisture content - around 6 - 8%
  • Higher energy content than firewood weight for weight
  • Require less storage space
  • Will burn cleanly on very low air settings
  • Longer burn times - up to 2 hours per briquette
  • Clean and pleasant to handle - no bark or creepy crawlies
  • One tonne of briquettes is equivalent in energy to around 4 tonnes of average air dried logs

The briquettes are produced at extremely high pressures, and get very hot in the process - often over 300 degrees centigrade. This causes lignins and resins in the wood to soften and then act as a natural glue to hold them together when they cool. There are no glues, binders, preservatives or additives of any kind - they are a 100% natural wood product.

Some types, usually the cylindrical ones which look like lots of discs stuck together, will tend to expand quite a bit once alight so don't overfill your fire or they could escape! This type should not be attacked with the poker once alight either or they will fall to bits. The best ones we've used are the ones we now sell - and they don't do any of the above! They have also been shown in tests to have a lower moisture content and higher energy and burn times than almost all of the competing products - AND they're made here in the UK rather than being imported. They are also a very consistent product, so they will always give good performance unlike traditional firewood which is different from one load to the next. The machinery used to produce the briquettes is quite fussy about what it's fed with, and so unless the material is just right, the process just doesn't work.

Wood pellets are a fantastic leap forward in wood fired heating - and pellet stoves are now on the market with heating efficiency's up to 90%. Compare that with an open fire which is likely to have an overall cooling effect on a house as it draws cold air inwards to feed it! However, generally speaking, wood pellets are best for use only in dedicated pellet stoves where they are drawn in a few at a time and burned very fast and very hot. Many of these pellet stoves can be turned on and off much like a gas fire - they don't need to be "in" all the time to keep them going. Pellet Stoves are still an expensive option but will come down in price as the technology develops and will be very common in the future we think.

Many people are surprised to find that a wood burning stove installer will want to, and often insist on lining what the customer thinks is a perfectly good chimney. Generally this is NOT just a ploy to make more money on the job!

Most existing chimney stacks in our houses were built to serve an open fire at the bottom of them, and providing they were swept now and again, they did a pretty good job. However, a modern wood burning stove and an open fire are very different animals. With an open fire, over 80% of the heat it produces goes straight up the chimney. This means the inside of the chimney is hot, and there is a huge amount of draft rushing up it.

Your modern stove on the other hand will be putting the majority of it's heat into the room, and using a lot less air in the process. This means that the chimney stack runs very much cooler inside, and the draft up it is much lower. Because the chimney isn't getting hot any more, any tars and creosotes in the smoke from your fire can actually condense on the inside of the flue and build up into thick deposits which present a risk of chimney fires and poor stove performance later on. These deposits can also attack the bricks and mortar joints inside the flue, and in some cases they can start creeping through walls, particularly in upstairs rooms to cause staining and smells. This can often be remedied only by cutting out and replacing the damaged brickwork - which will be expensive!

This is why the use of a chimney liner is recommended with a modern wood burning or multi fuel stove. Being a much smaller flue, the gases travel up it faster which means that any tars and so on in the smoke will get out of the chimney before they have time to condense. Sometimes a liner can be insulated - this is to keep it hotter to help avoid the condensation of deposits already mentioned.Burning good quality well seasoned wood will also help a great deal towards keeping your chimney clear of deposits, as will using wood briquettes which are very clean burning due to their low moisture content.

Obviously it's down to your individual conscience at the end of the day, but we would strongly advise against it. Old fencing may well be tanalised (wood often with a greenish tint to it) The original Tanalith wood treatment formula used copper, chromium and arsenic and as well as throwing nasties out of your chimney for everyone else to breathe, toxic compounds are concentrated in the ash it leaves behind.

MDF and plywood/chipboard etc contain all sorts of chemicals including preservatives and formaldehyde and they give off some very unpleasant compounds when burned. They should be burned only in industrial incinerators where temperatures are high enough to break down these compounds completely. There are businesses selling MDF off-cuts on Ebay as firewood - this is probably illegal as well as being an extremely bad idea for you, your neighbors and the planet in general.

Painted and treated wooden window frames can be equally unpleasant, with the obvious risk of lead based paints being used on them at some stage.

We would ask that all stove users please give a little thought to their neighbors, and think about whether they would mind their own kids running about breathing in toxic fumes from someone else's stove.

Chances are that if the flue is clear, then the problem is with the wood rather than the stove. Properly seasoned firewood will make an excellent fire in almost all cases. Invest a few pounds in a moisture meter or call round and I'll test it for you. Remember that with firewood, you often do get exactly what you pay for!