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Is it a Bad Idea to Burn Softwoods?

Q: I notice that your fuelwood chart lists many softwoods (fir, pine, etc.). Although I haven't seen anything specific on your website regarding this subject, I always understood that one should NEVER burn softwoods as fuel. I would be very interested to hear your comments. You have a superlative website, and I really wish you made housecalls to Norristown, PA.

Robert Monaco

Sweepy A: You hear all sorts of negative things about softwoods. Some have basis in fact, and some don't. The folks who live here in the Pacific Northwest, and other places where hardwood species don't proliferate, burn softwoods like Pine, Alder and Douglas Fir out of necessity. Contrary to popular folklore, we softwood-burners haven't blown ourselves up, and our children don't have webbed toes. Here are some legends you hear about softwoods, and the facts.

1) Softwoods cause more creosote to form in the chimney.
False. The creosote issue is about water content, not resin content. The high resin (pitch) content of certain Fir species actually gasifies readily, and burns hot and clean. It doesn't "turn into creosote" in the chimney, as some folks would have you believe. HOWEVER: high resin content can allow wood to burn readily while still not dry enough to burn properly. Often, people simply don't give Fir enough time to season, and wind up burning it while its moisture content is too high. Which results in heavy creosote formation, and the popularity of this piece of folklore.

2) Softwoods don't have any heat value.
False. Actually, all wood species have about the same heat value, pound for pound. But, if you'll have a look at our fuelwood chart, you'll notice that a cord of hardwood weighs more than a cord of softwood. A load of high-density hardwood contains more wood fiber than a load of low-density softwood, so it has more heat value. This means you might have to burn more PIECES of softwood to heat the same area, but you're actually burning about the same WEIGHT of wood fiber. Admittedly, at a certain point you have to factor in the frequent loading necessary to heat with the bottom-of-the-chart species, and decide if the extra effort is worth it. For example, you wouldn't want to heat your house by burning Balsa wood.

3) Softwoods form a lot of ash.
True, in some cases. Some Fir species have extra-thick bark, which, when burned, leaves a lot of ash behind (sort of like paper does). Many people here in the Northwest who burn Douglas Fir, for example, will remove the bark during the splitting & stacking process (the really thick stuff pops right off) so they don't have to shovel their stoves out so frequently.

4) Softwoods burn smokier.
False. In fact, the super-low emissions numbers scored by today's EPA approved woodstoves were all achieved while burning Pine.

5) You can't hold a fire all night with softwoods.
There is some validity to this idea, due to the same fact discussed in #2 above: when you bank your fire at night, you can't get as many pounds of softwood into your stove as you can hardwood. It takes a tightly-constructed stove with a decent size firebox to go the night on a load of softwood.

6) Softwood burns too hot, and can damage your stove.
Some glimmer of truth here, pertaining to all Pine species, and especially to some extra-high-resin woods like Fatwood or Cedar. Due to the high combustibility of wood pitch, these species want to burn HOT and FAST. One trick to compensate for this is to mix these with other species in the same load. Many people simply split them up extra-small and use them as kindling, because they ignite so readily and burn so hot. A third technique is to turn the stove's draft control down a little further than usual to keep the fire under control. This third technique requires some care that you don't turn the draft control down too far and smolder the fire, or excessive creosote formation will result (which is another reason softwoods get the creosote rap discussed in #1 above).

 

       

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