Resources & Tools

Wood Pellets Glossary

Whether you’re a newbie or an old hat in the world of wood pellets, you’ve probably heard some terms that make you wonder… ‘What the heck’s a skid?’

Here’s our plain-English guide to the terms we’re most often asked to explain — organized by what they describe: the fuel itself, the stove that burns it, and the delivery that gets it to you. And don’t be shy: if we missed something you’ve been wondering about, give us a call at 1-800-PELLETS and we’ll be happy to help.

Fuel & Quality Terms

Term	What it means
Ash content	What’s left over after pellets burn, measured as a percentage of the pellet’s weight. Lower ash = less stove cleaning. Premium hardwood pellets run under 1.0% ash; premium softwood pellets are typically under 0.5%.
Biomass	Any organic material that can be used as fuel. Wood pellets are a biomass heating fuel — as are wood bricks, cordwood, and corn.
BTU (British Thermal Unit)	A unit of heat energy — technically, the energy needed to warm one pound of water by 1°F. Pellets are rated in BTUs per pound: the higher the number, the more heat per bag. Premium pellets range from roughly 7,700–8,300 BTU/lb for hardwood to 8,000–8,800 for softwood.
Clinker	A hard, fused chunk of melted ash that forms in the burn pot. Usually caused by high-ash or contaminated fuel, or a burn pot overdue for cleaning.
Creosote	A flammable residue that forms when wood smolders with too much moisture and too little air. A firewood problem far more than a pellet problem: dry pellets in a hot, forced-air stove produce very little creosote.
Fines	The sawdust and small pellet fragments at the bottom of a bag, created by handling and shipping. A small amount is normal; excessive fines suggest soft, poorly compressed pellets.
Hardwood / softwood pellets	Pellets made from deciduous trees (oak, maple) or conifers (pine, spruce, fir). Despite the firewood rule of thumb, premium softwood pellets often deliver more heat and less ash than hardwood. Quality matters more than species.
Lignin	The natural, energy-rich ‘glue’ in wood fiber. Heat and pressure at the mill activate lignin to bind pellets together — no chemical additives needed. Softwood’s higher lignin content is why it often burns hotter.
Moisture content	How much water remains in the pellet, as a percentage of weight. Premium pellets are dried to about 4–6% — a fraction of even well-seasoned firewood. This is why they ignite fast and burn hot and clean.
PFI Standards	Quality specifications published by the Pellet Fuels Institute, the North American industry association. ‘PFI Premium’ grade sets limits on ash, moisture, density, size, and fines.
Wood bricks (biomass bricks)	Dried, compressed sawdust and chips formed into blocks — think of them as giant pellets for a regular wood stove or fireplace. A cleaner-burning, easier-storing alternative to cordwood.

Your Stove & Its Parts

Term	What it means
Airwash	A built-in air system that sweeps combustion air across the inside of the glass to keep soot from sticking. A dirty airwash inlet is a common cause of blackened glass.
Ash pan	The removable tray that collects ash below the burn pot. Emptying it every few days is the most basic pellet stove maintenance.
Auger	The motorized screw that carries pellets from the hopper to the burn pot. Your feed rate setting controls how fast it turns.
Burn pot	The small chamber where pellets actually burn. Its air holes must stay clear; a dirty burn pot is behind many ignition and flame problems.
Combustion blower	The fan that pulls air into the fire and pushes exhaust out the vent. (The convection blower is its partner which circulates the heated air into your room.)
Damper / airflow setting	The control that adjusts how much combustion air reaches the fire. Balancing airflow against feed rate is the heart of pellet stove tuning.
EPA-certified	A stove tested and certified to meet U.S. EPA particulate emissions limits. Certified pellet stoves typically run at 70–83% efficiency.
Feed rate	How fast the auger delivers pellets to the fire. Higher feed = more heat, as long as airflow keeps up.
Heat exchanger	The metal passages that transfer the fire’s heat to the air blown into your room. Keeping it clean is the difference between heating your house and heating your chimney.
Hopper	The fuel bin on your stove where you pour the bag of pellets. Empty it at the end of each season — pellets left all summer absorb humidity and can jam the works.
Igniter	The electric element that lights the pellets automatically. A slow-starting stove often means a weak igniter or a dirty burn pot blocking its airflow.
Pellet insert	A pellet-burning unit installed into an existing fireplace opening, as opposed to a freestanding pellet stove or a whole-home pellet furnace/boiler.

Delivery & Handling

Term	What it means
Skid (a.k.a. pallet)	The wooden platform your bags of pellets are stacked and wrapped on. Skids come in different weights from 50 bags (1 ton) to 75 bags (1.5 tons).
Ton	The standard unit for buying pellets: 2,000 pounds, or fifty 40-lb bags. A typical home burns 2–5 tons per heating season, depending on climate, home size, and usage.
Shroud	The heavy plastic wrap sealed around a skid at the mill to protect the bags from weather. Keep it intact as long as possible — it’s your fuel’s first line of defense outdoors.
Slip sheet	The cardboard layer between the wooden pallet and the bottom bags. Together with the pallet, it keeps your pellets off damp ground or concrete.
Pallet jack	A hand-operated lifting machine our drivers use to move full skids over smooth, hard surfaces; like rolling a ton of fuel into your garage. Not to be confused with a hand truck.
Hand truck	The familiar two-wheeled upright dolly — handy for moving a few bags at a time, but not what moves a full skid. That job belongs to the pallet jack.
Driveway delivery	Our free standard delivery: a skilled driver places your full skids in your driveway using a truck-mounted forklift. You don’t need to be home.
Garage delivery	Our premium option: the driver places skids directly inside your garage using an electric pallet jack (smooth concrete floor and clear access required).

Still wondering about a term you heard? Call the Pellet Experts at 1-800-PELLETS — explaining this stuff is our favorite part of the job.