Wood Stoves: Safety First
Wood stoves provide reliable heat, but make sure that yours is safe and efficient
Nobody speaks of this contest but everybody knows who’s winning. It’s how we get out the competitive impulse in rural Vermont: we race to have the neatest woodpile. Admit it: even as you’re reading this, saying “that’s not me,” you’re mentally comparing your woodpile with the neighbor’s.
There is no question about who is the winner in my neighborhood — the toymaker — and he flaunts it, building these perfect stacks in the middle of his lawn, near the road. After Hurricane Irene, I had a conversation in passing with someone I had never talked to before, from a different part of town. I was inquiring if the toymaker’s house, situated on the river, was okay. Yes, he said — even the woodpile is untouched. We understood each other perfectly.
If you heat with wood, you’re a competitor, like it or not. I am in this game, and I do poorly. I cut a lot of top wood that others would leave behind, and it doesn’t make for neat stacking. That’s fine with me — I put my extra effort into keeping my wood off the ground and well covered. Dry wood wins my game.
Why wood heat remains popular
It’s the season to look at the popular practice of heating with wood. I heat with wood and have for my whole life. I like it for several reasons. I can cut and split my own wood, keeping my costs to a minimum, and giving me a sense of control over my family’s heat source. I’m not subject to the fluctuations of heating fuel prices, and I won’t have any problems from power outages or mechanical problems.
I also like the fact that I harvest firewood from the healthy, managed forest around my house — so at least in theory, there are no net carbon emissions (or minimal, when counting the chainsaw and some minimal transportation).
Downsides to wood heat include the labor involved and the fact that most homes need a backup system if you expect to be away for a few days in the middle of winter. Another downside is the problem of air particulates.
Don’t move firewood
Before getting into some of the safety details of stoves, let’s touch on a key item of ecosystem health: invasive insect species. Yes, I like eating insects, as discussed recently, but this is an area where I don’t mess around with them.
As the website DontMoveFirewood.org reports, “Tree-killing insects and diseases can lurk in firewood. These insects and diseases can't move far on their own, but when people move firewood they can jump hundreds of miles. New infestations destroy our forests, property values, and cost huge sums of money to control.” Those insects include the emerald ash borer and the Asian longhorn beetle—feared pests that threaten economically and ecologically important hardwood forests in Eastern North America.
The recommendation is to use firewood from the most local source possible—under 10 miles is ideal, and over 50 miles is probably too far.
Watch out for hazardous air pollutants (HAPs)
Smoke resulting from incompletely burned wood contains hazardous air pollutants or HAPs (which may cause cancer), fine particle pollution, and volatile organic compounds (VOCVolatile organic compound. An organic compound that evaporates readily into the atmosphere; as defined by the U.S. Environmental Protection Agency, VOCs are organic compounds that volatize and then become involved in photochemical smog production.). Particle pollution in smoke can damage lung tissue and lead to serious respiratory problems when breathed in high concentrations.
In low concentrations, particle pollution in wood smoke can harm the health of children, the elderly, and those with existing respiratory diseases. Burning seasoned wood in an EPA-certified wood stove minimizes this risk, but doesn’t eliminate it: where there’s fire, there’s smoke.
New wood stoves are worth the cost
I bought my first two wood stoves with the goal of saving money: they were relatively inexpensive, reconditioned units. Only last year did I give in and buy an EPA-certified wood stove, and I am glad I did.
EPA-certified wood stoves have to meet a limit of 4.1 grams per hour of particulate emissions for a catalytic stove, and 7.5 grams per minute for a noncatalytic stove. On average, this amounts to at least 50% less pollution, and possibly depending on how old and inefficient your particular model of stove is. Minimum efficiency rates are 63% for “noncat” and 78% for “cat,” although some stoves boast higher efficiency. Given the health risks of wood smoke, those reduced emissions numbers really make a difference. And the effort saved in a more efficient stove helps pay the cost difference.
Stoves built before 1989—less efficient, more polluting
Any wood stove built before 1989 is not EPA certified, and is likely to be much less efficient and much more polluting then a stove built since then. While older wood stoves tend to rely on pretty basic baffles to burn as cleanly as possible, newer stoves do this better with insulated fireboxes that keep the fire hot, and more sophisticated after-burn systems. And they are laboratory-tested, so we know they work as designed, unlike older stoves that rely on someone’s half-baked idea of how wood smoke “ought” to travel.
I can say from experience that the new models work a lot better, and the $300 federal tax credit can help pay for them. When you install it, have a professional do it to make sure it’s done safely.
Dry firewood, and professional cleaning are key
Burning only clean, dry, and seasoned hardwood that has been split and dried for at least six months is also essential for clean, efficient burning. Properly seasoned wood is darker, has cracks in the end grain, and sounds hollow when smacked against another piece of wood.
Another step that I have been less-than-religious about in the past, is to have a professional chimney sweep inspect my wood stove and chimney on an annual basis. Here again, I have learned my lesson: wondering why I couldn’t get a fire going this fall, I called my local chimney sweep, who promptly removed the creosote blockage from my cap and chimney. Chimney sweeping is a pretty easy DIY job for many homes, but it's only a DIY job done if you actually DIY... if not, time to call the pros, who do a great job.
Hot gases from the fire condense on the chimney to form creosote, particularly in cold locations like the cap. Keeping your chimney clean may not be as visible an effort as keeping that wood pile neat, but it can help prevent a dangerous chimney fire or an unpleasant back draft. Oh yes, it’s common sense, but worth saying: when removing ashes, deposit them in a closed metal container. Stay warm, and stay safe!
Tristan Roberts is Editorial Director at BuildingGreen, Inc., in Brattleboro, Vermont, which publishes information on green building solutions.
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