Sometime ago I wrote a post called, A Word About Pellet Stoves where I basically trashed pellet stoves based on my experience with one over several years. I stand completely by that post….however…I received a question about wood pellet stoves, specifically wondering if I could tell them if there was any difference between the heat produced from hardwood pellets vs softwood pellets.
It seems the latest gimmick in the pellet business is to manufacture the pellets from hardwood which most folks believe will result in more heat. Unfortunately that is not true. In fact, it seems that softwood pellets actually create more BTU’s than hardwood. (British Thermal Units a measure of heat) This is because of the manufacturing process.
Hardwood firewood is denser than softwood firewood. That is partly why softwood makes good kindling and is great for quick fires, while hardwood burns longer and hotter.
Firewood is sold by volume i.e. cord, which is not the same as weight. Pellets are usually sold by weight, 40 pound bags. When the pellets are manufactured the wood chips are ground into sawdust and compressed into pellets held together with a glue binder. The compressing makes the density the same for softwood as it is for hardwood.
The density of the pellets are determined by the pellet mill and generally will average 42-44 pounds per cubic foot. With one difference, the softwood usually has some resin pitch in it that is believed to cause the softwood to burn a little hotter. I’m not going to go into it all now, because I am too lazy and already wrote this post only to lose it…so now I am condensing things a bit…sorry…
There are typically two kinds of pellets sold, premium and standard. Premium pellets have a low ash content, meaning they will produce less ash and crud in your pellet stove burn pot and stove, and less ash and soot in your chimney. The standard pellets have a higher ash content thus more mess. So look on the bag for ash content, it should be 1% or less. When it comes to ash content, that is generally due to the soil where the trees were grown and either softwood or hardwood can be very low in ash content, so that is not a factor in terms of hardwood vs softwood pellets.
Instead of concerning yourself with hardwood vs softwood, the best idea is to look on the bag for the BTU’s. The best pellets should produce around 8000 BTU’s and above, although most will show somewhere between 7500 and 8500. Go for the higher.
In most instances you will find that softwood pellets have a higher BTU because softwood pellets usually produce 10-20% more BTU’s per pound than hardwood depending on the species.
For example, one website I visited claims that White Oak (hardwood) 8810 BTU/pound vs Yellow Pine (softwood) is 9610 BTU/pound.
I’m telling you all this because I know that pellet stoves are gaining in popularity every year, especially with high oil prices and claims that they are better for the environment than fossil fuels. I am not knowledgable enough to even begin to argue that one way or the other.
Be cautious of hardwood pellets called ‘premium’ Don’t take them at face value, because the price will likely be higher. The high price is actually a reflection of higher manufacturing costs because the raw materials cost more, not because they are better or burn hotter. They don’t. Look for high BTU’s and low ash content.
Oh yes, longer pellets vs shorter pellets….Some pellet stove owners believe in the longer pellets, others the shorter pellets. I don’t think it matters, it just looks like it does.
Here’s why: chances are you will have to slow down your auger speed with shorter pellets because they will fall through the hopper quicker, putting more in the burn basket. The longer ones go through slower, so the higher auger speed is necessary to maintain the same heat. So if you have been burning the longer pellets and move to the shorter ones, and find yourself turning down the auger, you might think that they are more economical….think again…The outcome is essentially the same in terms of heat.
**Note: Since I wrote this post I was corrected by a reader, there is no glue used as a binder in the manufacture of wood pellets, it is the resin in the wood that when compressed binds the materials together.** Thanks Anonymous! I stand corrected.
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