Wood Heat: A Guide to Heating Your Home
Selecting and Curing the Right Type of Wood Can Save You Money and Time
By Alexis Griffee, Florida
As energy prices continue to soar, people are turning back to natural heating methods and away from gas and central heat. Woodstoves and fireplaces are making a comeback in homes across the nation as we seek more affordable and self-reliant options to heating. While the idea of using wood to heat your dwelling is nothing new, it does require some more forethought than simply flipping a switch. When it comes to using wood for heat, there are several factors that come into play. Various qualities of different types of wood as well as how the wood was cured will greatly affect the wood burning process. Through some initial forethought on sizes, types and amounts, switching to wood heat for your home can be a seamless transition.
Wood heating is only as effective as the wood that you use. Different types of wood will have different qualities such as burn time, density, and even spark characteristics. Additionally, some types of wood create a hazard when burned, either from increased tar buildup in your stove or toxic smoke. Knowing the characteristics of the wood that you burn will increase the efficiency of your heating as well as make your money go farther by choosing longer burning hard woods.
The burning efficiency of different types of wood is commonly measured in British Thermal Units, or BTU per cord of wood. A BTU is the amount of heating energy available in a substance, and in this case, firewood. When speaking of the BTU ratings of a wood, it is measured by the cord of wood. The number given, often in the teens and 20s, is representative for that many million BTU per cord. To break down a BTU even further, the burning of one match is approximately equal to one BTU. In comparison to regular electricity, 3,412 BTU are equal to one kilowatt hour.
As you probably know, wood is generally sold in volumes called cords. However, not all cords are created equal! There are three main ways that people price and sell wood. The most common method of measuring firewood volume is a standard cord. A standard cord is 4-feet by 4-feet by 8-feet and has a total volume of 128 cubic feet. Another method that is often confused with the standard cord of wood is the face cord. A face cord is four feet high and eight feet long, but can be any width! The total volume of a face cord averages from 32 to 48 cubic feet. The third and final most common method of selling firewood is by the pickup bed or pickup load. While this term can vary greatly, it usually implies approximately 64 cubic feet of wood. Understandably, a neatly packed truck bed of wood will contain more than a load that is haphazardly tossed in. If you purchase wood via this measurement method, ensure that the wood gets stacked neatly in the truck bed to ensure that you get the maximum amount of wood for your money. Understanding which cord measurement your seller is going by before buying firewood will help you make economical choices that will greatly aid your pocketbook this winter.
As a general rule, when choosing a type of wood to burn, you want to choose a dense wood. More weight per volume allows for longer burn time. For example, even though size wise, a cord of a softer wood will be the same size as a denser wood, you will get more burn time from the heavier wood. Softer woods may have other characteristics that make them desirable, but they should not be chosen as the bulk of your heating stock if other denser woods are available.
On average, wood curing takes six to nine months. In more humid climates, many people choose to cure their wood for a year to ensure proper burn ability. For optimal burning efficiency, you want the wood to be below 20 percent for moisture content. Green, or uncured wood, can have moisture contents of 45 percent or more. Uncured wood is problematic on multiple fronts. Since uncured wood has higher moisture content, it does not burn as efficiently or as hot as cured wood.
The smoke of uncured wood creates two problems. First, uncured wood puts you at an elevated risk of creosote buildup within your chimney. Creosote is the result of the oils in the wood not getting hot enough to be properly combusted and utilized as energy for the fire. These oils are then dispersed as a gas in the smoke causing buildup in your chimney. Additionally, the heavy and volatile smoke of wet wood actually cools the flue. When the flue is cool, it does not effectively burn off the resulting creosote buildup. The buildup of creosote is a major hazard for fires. It is estimated that in the United States, creosote buildup is to blame for 73 percent of heating fires. Despite these potential risks, creosote buildup can be controlled when you burn proper wood and follow recommended cleaning procedures for your chimney and stove pipe.
Aside from the safety reasons, buying seasoned or cured wood is also important for maximum financial benefit. Once wood has cured, and its moisture content is reduced, it loses size, which will translate to you getting more wood for your cord size. This will also reduce the overall weight of your wood making it easier to stack and store.
The type of wood that you use for your heating needs will be greatly impacted by your geographic location. A wood that is common in California will not be the same as Florida, and vice versa. Each different species has unique qualities that make it ideal, or not, for heating and other uses. This is where a bit of research and knowledge can really prove beneficial to your pocketbook! Some species may not burn as hot, or as long as another that is available in your area. If you choose an inferior species of wood, your money will not go as far and your electricity conserving efforts may be in vain.
BTU rating: 32.9
Splitting difficulty: Easy
Without a doubt, the wood burning all-star is osage orange. Although its fruit can be regarded as a nuisance, this tree is beloved by those who use it for their wood burning needs. Osage orange packs an amazingly high BTU rating of 32.9! Native to Oklahoma, Texas and Arkansas, osage orange is a regionally specific tree even though its burning capabilities are infamous. Osage orange wood is a low smoking, easy to split wood.
BTU rating: 24.4-26.5
Splitting difficulty: Easy
The qualities of oak vary greatly depending on the species of oak that you are burning. On average, species like the Red and Black oak have 24.4 million BTU per cord. Similarly, White and Bur Oak are 26.5 million BTU per cord. Oak is one of the species that is very area specific. It is also very easy to confuse the different types of oak, especially if you purchase your wood precut. Oak is also generally regarded as a wood that is easy to split. This is good news for those who prepare their wood with hand tools! Additionally, the fact that if properly cured, oak is generally a low smoking wood, make this an ideal burning wood if it is readily available in your area.
BTU rating: 21-23
Splitting difficulty: Hard
Maple is another common choice for heating. Maple wood is actually regarded as slightly toxic, so it should be tested in small amounts before making up the bulk of your firewood stores. Maple is not the best choice for wood burning, but still rates relatively high on the BTU scale. The highest rated maple wood for burning is the sugar maple at 23 BTU per cord. Following closely, the black and red maple are tested at 21 BTU average.
BTU rating: 25
Splitting difficulty: Hard
Another one of the most highly prized hardwoods for use in heating comes from the hickory tree. Hickory wood is famous for its density and strength, all factors that make it an ideal candidate for home heating use. When it comes to BTU per cord ratings, hickory wood is a heavy hitter averaging over 25 BTU. There are several different types of hickory and despite this range in species, all of them are well regarded when it comes to use for home heating. However, to some, the same advantage that hickory wood has is also its greatest pitfall. Hickory is renowned for its density and strength. While these factors make it a hot burning wood, they also make it harder to cut and split than some of the softer trees available. For those who cut and split their wood by hand, Hickory may not be the ideal choice for your heating needs.
BTU rating: 16.1
Splitting difficulty: Easy
Cottonwood is a softer wood, so it is not an ideal choice as the main bulk of your heating needs. At only 16.1 million BTU per cord, its abilities are far behind other more dense woods like oak. However, cottonwood does provide a benefit to your heating needs. Cottonwood is a very easy wood to start burning. This provides a valuable tool to help start your fire so that you can add in your main heating wood once the fire is lit and well established. Additionally, cottonwood is also readily available in many parts of the United States. Since most people do not use it as their main burning wood, cottonwood can be an economical option for part of your heating needs.
There is a general thought process that if it is wood, it is good to burn. While that can be true, it can also be problematic and potentially hazardous. Some woods not only have qualities that make them dangerous to burn due to buildup in your chimney and stove pipe but can be dangerous to your health. Some wood species, like mimosa, for example, can be lung irritants. While this may not be problematic to all people, those who already suffer from lung ailments, and young children in particular, can be affected greatly. On a more hazardous note, yew (Taxus genus) is an extremly toxic wood to burn. Far more than just an irritant, it is a direct toxin and can cause nausea and cardiac problems. If you have sensativities or are new to burning wood, it is advised that you err on the side of caution and use properly cured, common wood burning species.
Anytime that it comes to using fire for any purpose, safety has to be your number one priority. It is paramount that you always ensure that your home has working smoke detectors with fresh batteries and that your chimney and stove is in proper order before entering the colder seasons where heating is required. When done responsibly, wood burning can be a major advantage financially. Knowledge of the different qualities of wood as well as proper cord sizes is paramount to making your wood burning ventures a financial success.
Through some research and planning, your winter can be a warm one!
Alexis Griffee writes from her home and tends to her garden, bee and livestock in Milton, Florida.