Greenfires Chimney and Stove Services

  It is a sad fact that there is an awful lot of rubbish being sold as firewood these days. With gas and oil prices going through the roof in recent years, there has been a huge increase in sales of woodburning stoves, and a corresponding rise in the number of "firewood merchants" setting up to supply their owners.Many of these outfits are genuine, but unfortunately there are quite a few out there who have just seen this as a chance to make a quick profit by selling anything they can get their hands on, often within days of it being cut down. There is also an opinion amongst many new owners of woodburning stoves that firewood should be cheap, "because it just grows everywhere", and so they will look for the cheapest price they can find and buy on that basis. These are the people who are most likely to be disappointed.

Producing and selling good quality firewood is not a business that is going to make anyone rich in a hurry! Buyers who think the price is high "for stuff that grows everywhere" should take a moment to consider how the wood got to their doorstep.

The firewood merchant will have to purchase the wood to begin with, either as standing trees in a wood, or felled trees cut into lengths. If standing timber, he needs to pay for travel to the site, felling the trees, cutting them up, getting them extracted from the forest, loading them onto a vehicle and transporting them back to his yard. If purchased as lengths at the forest roadside, the purchase price will be higher as he's paying someone else for all the felling and extraction costs. Once back at his yard, which he is very likely to be paying rent and business rates on, the timber will have to be unloaded and stacked to season. It will have to sit there for a minimum of a year, and often two years or longer. Once eventually seasoned, the wood will have to be moved again and cut again to firewood lengths, and then split to size, before being loaded onto another vehicle and finally delivered and unloaded, usually by hand, at the customer who may be some miles away. Only at this stage does the seller see any return on the money he spent maybe three years ago, and has been spending on this wood ever since, and when you take into account the number of hours he has actually spent moving, stacking, cutting, splitting and delivering the stuff, plus the costs of fuel for the chainsaws, vehicles, wood processors and so on, it suddenly dawns that the product is not that expensive after all!

Cheap firewood is likely to be stuff from garden clearances etc that is freshly cut, and wet through. Some people will try and sell it on as it's cheaper for them than taking it somewhere and tipping it. If you can actually get it to burn at all, it will give out very little heat, but lots of smoke containing tars and creosotes that will coat the inside of the chimney and could eventually lead to a chimney fire, as well as damaging brickwork and mortar joints, and maybe seeping through bedroom walls where the chimney passes through causing staining and smells. Wet or unseasoned firewood is a waste of time - as the water in it must be driven off before it will burn properly and give out any decent heat. The energy to drive off that moisture comes from the wood itself, meaning that there's very little left to heat your house by the time it's actually burning properly - if indeed you can get it to do anything more exciting than smouldering. We know of people locally who have bought logs from garage forecourts and have not actually been able to get them to burn they are so wet!! Others have said that they need to use coal as well just to get the wood to burn!

With firewood, you often get what you pay for.

HARDWOOD OR SOFTWOOD?

Both hardwoods (oak, ash, beech, alder etc) and softwoods (larch, spruce, pine etc) make excellent firewood. It's an urban myth that softwoods are no good - in fact in many European countries where they are way ahead of us in woodburning circles, they use softwoods almost exclusively. Softwoods do burn faster than hardwoods as they are less dense, and have slightly less energy on a log for log basis, so generally command a slightly lower price. Some places sell softwood as "heat logs" and hardwood as "long burning" but they are both excellent fuels when properly seasoned. There are very few woods that do not make reasonable firewood when properly dried, and a seasoned softwood log is always much better than an unseasoned hardwood one.

BUYING FIREWOOD

Customers 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)

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

"Cubic metre bags" Many people think that your common or garden builders bulk bag is a cubic metre. 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 1metre x 1 metre x 1 metre contains one cubic metre. A bag 90cm x 90cm x 90cm looks almost identical and yet only contains 0.72 cubic metres. If you have 70x70x70cm bags, which still look pretty big, then surprisingly you only have 0.34 cubic metres - a BIG difference if you're paying for what you think is a cubic metre!! If in doubt - tape measure out!

"Seasoned" 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.

"Does species matter?" 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 mould, 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.

"Fancy firewood" 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 woodfuels 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.

"What are these firewood briquettes I've seen?" These are a relatively recent product and are made from sawdust and woodshavings 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 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.

"What about wood pellets?" Wood pellets are a fantastic leap forward in woodfired heating - and pellet stoves are now on the market with heating efficiencies 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.

"I want a woodburning stove - do I need to line my chimney?" Many people are surprised to find that a woodburning 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 woodburning 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 draught 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 draught 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 woodburning or multifuel 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.

"Can I cut up and burn this old fence/chipboard/mdf/plywood/window frame etc?" 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 offcuts on ebay as firewood - this is probably illegal as well as being an extremely bad idea for you, your neighbours 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 neighbours, and think about whether they would mind their own kids running about breathing in toxic fumes from someone else's stove.

"My stove won't go - is it faulty?" 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!

Any questions? I am happy to offer advice on any aspect of woodfuels. Just use the "Contact us" link in the main menu.