From Your Forest Newsletter Vol. 4
Firewood
Some information and advice on firewood.
“A long straight row of firewood standing in the yard in springtime is like money in the bank. It is indeed. As it dries in the summer sunshine, you're collecting interest." - old adage
Wood is a renewable resource – but it is also a finite resource
- Typically there are about 20 cords of wood per acre. In general, each acre grows about 0.3 cords per year, meaning on a 10 acre parcel, you could harvest 3 cords per year without dipping into the 200 cords that are always there. The 200 cords is like the principal in a bank account, the 3 cords is the interest.- trees grow back where others have been cut. But forests have limits and forest soils can be depleted - wood is a carbon neutral heating source o CO2 released through burning will be taken backup by the tree that takes its place - local product o supports the local economy – landowners, forester, loggers, truckers - trees must be harvested wisely to protect the forest ecosystem
- efficiency should be considered to lessen the impact on the forest
Wood as a fuel
- types o typical firewood, pellets, chips - type and size depends on type of burning device o fireplace, woodstove, pellet stove, outdoor woodstove/boiler, gasifier - species o hardwoods better than softwoods * most hardwoods found in Vermont work well * beech, sugar maple, hickory, oak, black birch are on the high end of heat content * white birch, cherry, red maple are on the low end of heat content * popple and basswood have a very low heat content and are typically not sold as
firewood o softwood have resins (pitch) that greatly increase creosote buildup in chimneys and thus
softwoods should not be used, except in outdoor woodstoves.
- units of measurement o cord – 128 ft3 of wood, bark and air * standard dimensions of a cord is a pile of 4 feet wide by 4 feet tall by 8 feet long * a cord of 16” firewood stacked in a single row 4 feet high is 24 feet long o “face-cord” – a single row of wood of unspecified width that is 4 feet high and 8 feet long * * not a typical way to sell wood and buyers should be careful of this measurement - cost o $2.41/gallon heating fuel = $321/cord of dry firewood to get the equivalent heat value o $5.00/gallon heating fuel = $665/cord of dry firewood to get the equivalent heat value
Acquiring wood
- harvest from your own land, have a logger deliver a load of logs (20-30’ lengths, up to 14 cords per load), buy processed firewood to meet your specs o if harvesting from your own land, cutting trees down is very tricky and dangerous * Game of Logging training – course designed to teach people how to safely cut trees
* on the web at www.woodlandtraining.com
Processing firewood
- processing firewood involves taking a log and cutting it and splitting it into a desired length and size to fit in a wood burning device - as low tech as a cross-cut saw and splitting maul or as high-tech as a $100,000 fully mechanized unit - typically a homeowner wood use a chainsaw and a wood splitter o cut to the proper length as specified for a particular wood burning device * typically 14-24”
Moisture content of wood
- moisture content of wood directly affects the success of heating with wood - live trees have a moisture content on average of 50% - half the weight of freshly cut wood is water - the target moisture content for firewood ready to be burned is 15-25% - drying time depends on size of wood, species, relative humidity and temperature (largely a function of time of year), and exposure to sun and wind - on average it takes 4-6 months to adequately dry wood as long as the wood is subjected to sun and airflow
The benefits of using dry wood
- more efficient – dry wood produces more heat to the home because less energy is spent boiling off the excess water o 20% moisture content wood will give off about twice as much heat as fresh wood o more heat produced means less wood needed to heat a home - less work – increased efficiency means having to prepare less firewood for the season – that’s less cutting, splitting and hauling - less frustrating – fires with dry wood are much easier to light and much easier to keep going - safer – dry wood burns hotter and thus cleaner – there is more complete combustion of the wood and a higher chimney temperature means less buildup of creosote that can lead to chimney fires
How to dry wood
- start early – wood should be processed and stacked in the spring for burning the following winter - stack wood in a single row, in an open space, where it gets extended periods of sunlight and there is adequate airflow o running piles east-west or southeast-northwest is better than north-south because it will
optimize solar radiation - don’t cover the pile, with a few exceptions o it is OK to cover the top of the pile (with metal roofing, for example) but don’t cover the
sides. - once it’s dry – keep it dry: in the fall, get it inside o once it has dried adequately, typically in October, get the wood undercover to maintain its
dryness o if you don’t have any place to put it, and it is adequately dry, it is OK to cover it for the
winter, as long as the cover will keep out precipitation so the wood stays dry - if drying conditions aren’t adequate, it may take two summers to property dry wood
How not to dry wood
- don’t cut and split it o virtually no drying occurs through the bark – drying happens through the cut and split ends - cut it, but don’t split it o only cutting the log into “chunks” - leave it in a pile o only the top layer will dry, and still, this won’t dry well - cover it with tarps when it’s wet o tarps will only hold in the moisture – only cover well seasoned wood - stack it in the shade, or in back to back piles o wood needs sunlight and airflow to dry o multiple rows closely spaced cuts down on airflow
Miscellaneous
- heating with wood can be a lot of work - another old adage is that wood heats three times, once when you cut it, once when you split it and once when you burn it o you could get heated more than three times, depending on how many times you have to
move your wood - order wood early o whether buying logs or processed wood, get your order in early so that it has plenty of time
to dry
- buy logs and firewood from respected operators - be cautious of buying dry, processed firewood o check to make sure that you’re getting what you’re paying for - shop around o prices for logs and firewood can vary
Resources: general firewood information: woodheat.org heat value of various tree species: http://www.mb-soft.com/juca/print/firewood.html the importance of dry wood, explained: http://mb-soft.com/juca/print/311.html#green chainsaw safety/tree cutting courses (Game of Logging): www.woodlandtraining.com potential impacts of transporting firewood: www.dontmovefirewood.org general tree and firewood questions: Bennington County Forester (State of Vermont) – (802) 447-6501
* Important note: in order to reduce the chance of spreading exotic, tree killing pests and diseases that can wipe out entire species of trees, don’t transport firewood more than 50 miles – for more information, see www.dontmovefirewood.org
- MTW and JW | |