Heating With Wood

Reader Contribution by Cam Mather
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For years I’ve thought about putting together some basic manuals for my daughters in case they are ever at the farm and we are not here. There are often times after working in the bush cutting firewood all day when I suggest to Michelle that this may come sooner rather than later. Then I snap to my senses and realize there’s only way I’m leaving this place… in a fridge-sized cardboard box.

So here’s the first of a series of manuals for my daughters on heating with wood. I believe it will be helpful even for our city readers because as I recommend in my book Thriving During Challenging Times, having a back-up heat supply, like a woodstove, is a good idea no matter where you live.

The challenge with heating with a woodstove is using it properly and most effectively, which after a decade and a half here at Sunflower Farm, heating exclusively with wood, I think I finally get it.

Wood Selection

In The Renewable Energy Handbook by William Kemp (a book we published) there’s an appendix that lists the BTU output of various woods. Red Oak is 27,000 BTU/cord. Poplar is 18,500 BTU/cord. But there is a great reference that I’d like to emphasize here because of a number of questions posted by readers on my blog about cutting down a big pine tree on Valentines Day (romantic fool that I am) which is available here if you haven’t read it yet.

“All firewood has the same heating or carbon content PER POUND or kilogram of mass. However, the density of softwoods is much lower owing to increased air and moisture content, resulting in lower BTU content per unit mass.”

You can tell an engineer wrote this!

The chart also has an entry “Firewood by weight (all types) 8,000 BTU/lb.” So it doesn’t matter what you heat with, all firewood provides heat, you just need more softwood to do the same job. Many of our readers only have softwood near them, and that’s just fine, you just need to cut and burn more.

I find I am increasingly heating with softwood even though we own 150 acres of mixed hardwoods. This is because we are expanding the gardens around the house to run our CSA and to allow more sun to hit the gardens I am cutting back the trees, which are mostly pine and poplar. Yes they’re technically more work per unit of heat, but then again, they’re sort of not, because they don’t weigh as much once they are dry.

So, if I had a chunk of pine and a chunk of maple ready for the fire, and they were exactly the same volume and had both dried for one season, the maple would probably weigh almost twice as much. Trust me, with my aging arms I notice this. I’ve got to say that I kind of prefer softwood these days for this reason alone. It’s lighter!

So if your property only has softwood on it, don’t freak out. Just make sure you buy the absolutely most efficient woodstove you can and then just understand you’re going to need a larger volume of (in other words, more) wood to produce the same amount of heat.

My strategy for firewood is that right now I am cutting next year’s firewood. These are live trees I’m cutting down. So they will be cut and split by the spring, maximizing how much area of each piece is exposed for drying. They will sit outside in the heat or in the woodshed for the summer to dry. Our woodshed gets extremely hot during our summer heat waves so it’s like a wood kiln. I leave the softwoods outside because they are less dense and dry more easily. So by next winter the wood is amply dried and ready to go. Having a bit of moisture in wood doesn’t do any harm, as long as you burn the fire hot enough.

Burning it Hot and Avoiding Chimney Fires

When I wrote the post on pine lots of people seemed concerned about pine. They felt that the ‘pitch’ would plug up a chimney and cause fires. Any wood that is too wet (i.e. freshly cut and not dried enough) will burn inefficiently and deposit creosote on the inside of your chimney, which could potentially cause a chimney fire.

So there are three keys to avoiding a chimney fire.

Burn Dry Wood. Doesn’t matter what type it is, just don’t think you can cut a live tree in the fall and burn it that winter. You probably won’t be able to get it burning, but if you do, it will burn inefficiently and it’s dangerous.

Clean your Chimney Regularly. I used to clean my chimney every year, but because I follow steps 1 and 3, I found that there was no reason to clean it that often. I now clean it every second year. All that I ever find is some fine ash that’s deposited inside. There is no creosote. There is nothing that could burn or start a chimney fire. I shall continue to clean it regularly though, just in case.

Burn the Fire Hot. Here’s the trap we fall into some days. It’s kind of cold outside but not too cold. So there is a tendency to just keep throwing in the odd piece of wood once in a while and hope it will burn. The fire basically smolders and does not burn efficiently. This is the WRONG way to burn a woodstove.

You need to burn your fires hot. So once the fire has burned down to coals you need to put in lots of wood, stoke it up, get it roaring, then shut it down and let it burn in it’s proper airtight mode. This makes using a woodstove in the swing seasons much less convenient than say a natural gas furnace. But here’s the thing. A natural gas furnace and the CO2 that it emits are one of the things that are causing climate change. They’ve made the arctic so warm as to throw off the jet stream to create this polar vortex that is pulling all that cold arctic air south… all the way to Texas. So it’s kind of ironic that everyone’s had to crank up their fossil-fueled-powered furnaces to deal with the unprecedented cold, that these devices are compounding.

Carbon Neutral

That woodstove of yours is carbon neutral. You’re just putting back into the atmosphere carbon dioxide that the tree pulled from the air and stored in its woody mass. Zero carbon.

So … great for the planet, but less convenient in terms of heating. So you’ve got to ask yourself, are you prepared for this little inconvenience for the greater good? I know I am.

And this is the beauty of having softwood in your arsenal of wood to burn. When it’s really cold we have hardwood, but on those slightly warmer days we can load up our woodstove with softwood. We will get less heat, and it will burn down faster, but at least we can keep the stove burning efficiently to avoid creosote build up.

And remember, smoke is wasted heat. So if you’re outside your house and can smell a smoldering fire smell, you’re just wasting heat… and money. Get in there, stoke it up, get it roaring, and shut it down into airtight mode.

In the fall and spring it is usually too warm to keep the woodstove going all day. So we crank it up in the morning, get the house toasty warm and then let the fire die. The house will gradually get colder as the day goes on. This is when we’re envious of people with homes that are more efficient than ours because a well made home will hold onto the heat better. Then by late afternoon or evening we crank up the woodstove again, burn it hot, and then shut it down.

Heating with wood is more work than heating with a natural gas or oil or propane furnace. I would never argue with that. It is much cheaper if you cut the wood yourself. As the price of fossil fuel goes up, so does your savings with heating with wood. If you factor in the $500 health club membership you don’t have to buy if you cut your own wood, you are way ahead with a woodstove. Hey, make it a $1,000 membership for you and your partner, and you just saved $2,000! Yee ha!

But a woodstove is an amazing way to heat. It’s carbon neutral and allows you to grow your own fuel. And there is absolutely nothing as wonderful as wood heat. There is no substitute for having a woodstove in your living room that provides heat to your home. “And when I come home cold and tired, it’s good to warm my bones beside the fire.”

In my next blog post I’ll discuss my strategy for starting a woodstove.

Check out Cam’s website at www.CamMather.com.