Or
How much wood could a woodchuck chuck if a woodchuck could chuck wood?
I have been heating my home with wood for the past 40 years. I have a pretty good
How much wood will a wood burning stove burn in a season? There are many factors that must be taken into account, but on average three to six cords of wood are required.
The factors we will look at include; the
Measuring Fire Wood
Firewood is measured by the “cord”. The problem with a cord is the variance from one wood seller to another. By definition, a cord is 4 feet wide by 4 feet tall by 8 feet long. The area of this “cord” is 128 cubic feet. This seems simple enough but, no one burns (or can handle comfortably) 4 foot long logs, even after they are split.
The normal length of a log cut for burning is 16 inches. If logs are cut, split, and stacked in 16-inch lengths by 4 foot high by 8 feet long, this would be one-third of a cord. Many providers of firewood call this a face cord. The provider would have to sell 3 of these face cords to equal an actual cord.
Some providers cut their wood to 18 or 20 inches. To be sure you are getting what you are paying for or what you are told you are paying for, take a tape measure to the location where the wood is sold and check the wood pile. Do the math and verify the cut length of the wood.
Several other items will factor into the size of the load and quality of the wood that you will be paying for;
- Type of firewood. All wood is not equal. The species of the tree will be either a very hard wood (good) or very soft wood (not good) or somewhere in between. More on that later.
- Has the wood been seasoned? Seasoned wood is dry firewood. Nine months is the minimum that wood should be seasoned. This may add cost to the wood since the supplier has to store the wood during this time. My recommendation is to buy the wood unseasoned (usually cheaper) and season it yourself. Then you know how long it has dried out.
- Does the supplier deliver and for how much? Most firewood suppliers will deliver for free if you purchase a larger supply, two to three cords. This also saves loading and unloading, which is a lot of work unless you enjoy that!
- How tightly is the wood stacked? Depending on the type of wood and how it splits, the rack of wood may have quite a bit of air space between the logs which means less wood. Just something to be aware of
Types of Wood
If you have ever picked up a piece of red oak in one arm and a similar size piece of pine in the other, you know that the density (by the obvious difference in weight) of the oak is way more than the pine. Dense wood burns longer and hotter than the lightweight woods like pine and balsam.
The table below lists North American wood types from hardest, most BTU’s of heat, to softest with the least BTU’s of heat.
| Wood Type | BTU’s |
| Rock Elm | 32,000 |
| Shagbark Hickory | 30,600 |
| White Oak | 30,600 |
| Bitternut Hickory | 29,200 |
| Sugar Maple | 29,000 |
| Beech | 27,800 |
| Red Oak | 27,300 |
| Yellow Birch | 26,200 |
| Red Elm | 25,400 |
| White Ash | 25,000 |
| White Elm | 24,500 |
| Red Maple | 24,000 |
| Tamarack | 24,000 |
| Black Cherry | 23,500 |
| White Birch | 23,400 |
| Black Ash | 22,600 |
| Green Ash | 22,100 |
| Silver Maple | 21,700 |
| Manitoba Maple | 19,300 |
| Hemlock | 17,900 |
| Balsam Poplar | 17,260 |
| White Pine | 17,100 |
| Basswood | 17,000 |
| White Cedar | 16,300 |
| White Spruce | 16,200 |
| Balsam Fir | 15,500 |
This table is courtesy of woodheat.org
As the table states, different wood burns at different BTU’s or British Thermal Units. This is a unit of measure to gauge the amount of heat a source puts out. To heat an area, it will require a specific amount of BTU’s to raise the temperature from 32 degrees F to 72 degrees F. The higher the BTU output, the more heat you can get from that type of wood.
This does not mean you can only burn white oak and rock elm as firewood. Burning softer wood in the spring and fall is actually very efficient because the BTU’s required are much lower in the spring and fall. The outside temperature will be closer to 45 to 55 degrees, and it will not require as many BTU’s to raise the temperature of your home to 70 or 72 degrees.
Heating a Whole House or Supplementing
Many of you may not be burning wood 24/7 through the entire winter as some of us do. You may only want to supplement your gas, propane, or electric heat. A wood burner may only be lit during the day or only on extremely cold days.
There are several things you should consider when you are only burning wood occasionally. The wood you burn should still be seasoned properly. Wet wood will start poorly, and the smoke will deposit creosote in the chimney before it exists.
The chimney should be checked regularly (each time you light the stove) as lower burning temperatures (when the stove is going out often) will also deposit more creosote in the chimney.
Types of Wood Burning Stoves
For the purposes of this article, we will lump catalytic, non-catalytic, and pre-EPA regulated stoves into one category of “indoor wood burning stoves”. Each of these three operate differently, but for the purposes of this article burn relatively the same amount of wood.
Assumptions
First, we will assume that the colder the average temperature, the more wood you will burn. We will also assume for this article an average outdoor temperature in the winter of 30 degrees F in the daytime and 15 degrees F at night. Also that the burning season is from mid-October to mid-April which is five months.
Heating an 1800 square foot home with forced air through a wood burning stove will use about three to four cords (of the 128 cubic foot version) in a 5 month burning season. The added value of an indoor wood burning stove is the heat radiated directly from the stove into the room where it is located.
This type of stove also does not have to transfer the heat more than one time in a forced air system. My stove, for example, has the warm air around the firebox pulled directly into the air return for my propane furnace. The primary purpose of the propane furnace is to move the air from my wood burning stove throughout the home. The propane heat is only for a back up to my wood heat.
Outdoor Wood Burners
We call them outdoor wood burning stoves. The EPA and NFPA call them Hydronic Heaters. Regardless of the name, they are being installed all over the countryside. You will need some room if you are putting in an outdoor wood burner. To store wood!
Yes, there are advantages to having the wood burner outside. The wood stays outside. The mess, the mice, the dust, the bark, none of that comes in the house. So what is the disadvantage?
The wood you will burn! To heat the same 1800 square foot home is going to require five to six and one-half cords of wood. Yes, it all stays outside, but it takes a large pile of wood to heat the home each winter.
Let’s look at two reasons an outdoor stove requires so much wood. First, it is basically a boiler. The fire must heat the water to boiling temperature. Next, there is a transfer of heat from the firebox to the boiler water which causes a loss of efficiency.
The water must be pumped into the house in an insulated pipe. Next, the water is sent to a second transfer location in the house furnace exchange unit. Air from the cool air return is passed over the hot water pipes and sent out through the home’s duct system to warm the home. This is the second transfer of heat.
There is also no heat radiated into the room directly from the stove as in an indoor stove situation. This heat is lost outdoors unless the outdoor stove
These units work well and heat the home, but the loss of efficiency is noticeable. Especially if you are purchasing a supply of wood. If your supply of wood is free and plentiful, enjoy the inexpensive heat! Also enjoy the exercise as you cut, split, and stack the additional two to three cords of wood each winter.
The wood can generally be larger, so less cutting and splitting is required. On the other hand, those large pieces of wood have to be loaded into the stove. That requires a strong, young back, all winter long.
Additional Questions
Is a wood stove more efficient to operate than a propane furnace? A wood stove is more efficient than propane, but there are many factors to look at when determining efficiency. That is the topic of another article.
What are the best places to buy wood? Wood can be purchased from many different sources, some being tree trimmers, land clearing companies (excavators), and even sawmills. There are many more opportunities for firewood. Spend some time looking at my suggested list of places in my article on Best Places to Find Firewood.