Pellet Heating
The first appeal of pellets is their convenience. Bags of pellets stack compactly and store easily. A ton of pellets can be stacked in an area as small as four feet wide, long, and high, an area about half the space needed for a cord of wood. Bags of pellets can be stored in a small area of a dry garage, basement, or utility room or shed.
Pellets are also convenient because they load easily and cleanly into the stove hopper. Loading the hopper is normally required only once a day. The small size of pellets allows for precisely regulated fuel feed. In turn, combustion air can be regulated easily for optimum burn efficiency since the amount of fuel in the burn pot is predictable and consistent. High combustion efficiency is also due to the uniformly low moisture content of pellets (consistently below 10%). Uniformly low moisture, controlled fuel batches, and precisely regulated combustion air means high heat output and a very low level of unwanted emissions. As a biomass fuel, pellets offer the advantages of sustainable energy supplies through renewable raw materials. In addition, pellets are a by-product, not a primary user, of these renewable materials.
Using pellets reduces the cost and the problems associated with waste disposal. In 1993-94, more than 6.5 million cubic yards of waste were diverted from landfills and converted to home heating in the form of pellets. As part of the tradition of the hearth, pellet burning offers the enjoyment of fire viewing and active participation in providing winter comfort in the home.
What Are Wood Pellets?
All pellets are biomass materials, that is, products of commonly grown plants and trees. The most common residential pellets are made from sawdust and ground wood chips, which are waste materials from trees used to make furniture, lumber, and other products. Resins and binders (lignin) occurring naturally in the sawdust hold wood pellets together, so they usually contain no additives.
Hardwood versus Softwood Pellets
With a conventional wood stove you purchase your fuel by the cord; that means that the product value is measured in cubic feet and not by weight. For the ideal wood heating situation you want a good mix of soft and hard wood. Start your fire with the lower density, quickly burning soft wood, and then turn to the denser hard wood for a longer burn. The hardwood is denser and that is why it burns longer.
However, this does not translate into efficient pellet stove operation. Pellets are compressed sawdust, and all pellets have the same density. When sawdust is created it does not have the density of the original tree. The density of the pellet is not determined by nature but by the pressure in the pellet mill.
All pellets, whether softwood or hardwood, will have a bulk density of approximately 42 pounds per cubic foot. Therefore, burn times from pellets will be very similar whether, in fact, the length and diameter of the pellet determines the length of burn.
In terms of heat output, softwood pellets have naturally occurring resins, which contribute to heat output.
Independent laboratory tests show that hardwood pellets do not have more heat than softwood pellets. In fact, the tests have shown that softwood pellets tend to produce more B.T.U.’s per pound than hardwood pellets.
In fact, seasoned pellet stove owners consider other more important characteristics of the pellet; Does one brand of the pellets produce more ash or clinkers? Are the pellets more uniform in length than another brand? Is there a lot of sawdust in the bottom of the bag?
In fact, one of the pellet manufacturers in North America who make both hardwood and softwood pellets prints a similar message on the back of there pellet bags. To quote them, “Whether you burn hardwood or softwood in your pellet stove, you should feel good knowing you are lessening our nation’s reliance on imported fuels which contribute to global warming.” For more information check out our Pellet FAQ page.
Where Do Pellets Come From?
Pellet mills across the country receive, sort, grind, dry, compress, and bag wood and other biomass waste products into a conveniently handled fuel (Figure 1). Today, over sixty pellet mills across North America produce in excess of 680,000 tons of fuel per year, a figure that has more than doubled in the last five years. Pellets are usually packaged in forty pound bags and sold by the bag or by the ton (fifty bags on a shipping pallet).
- Check our our Pellet Special Offer Page
- Looking for accessories? Visit our showroom or browse our selection of hearth accessories online.
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