A freestanding wood-burning stove can provide
much of the ambience of a traditional masonry fireplace and do
so with efficiency ratings as high as 75 percent com pared with
a fireplace’s low or even negative efficiencies. Some stoves
can burn with their doors open, but all provide the most heat
when closed and properly vented. Part of the key to their efficient
heat transfer is the amount of exposed surface area; lined with
firebrick and built of heavy steel plate or cast iron, a wood
stove’s firebox radiates heat in all directions, warming sur
rounding objects and surfaces. For safety, minimum clearances
for combustible materials are mandated by codes and manufacturers
(see image at right).
Relative to a fireplace, a woodstove offers much more control
over combustion air intake and burn rates, but for peak efficiency and lower emissions, the smoke- exhaust temperature should stay
between 300°F and 400°F (150°C and 200°C). For this reason, don’t
buy more stove capacity than the space requires. It’s better
to install a smaller stove and burn it hot rather than burn a
too-large stove slowly to avoid overheating the room. Also, don’t
slow-burn a stove to make the fire last through the night; instead,
install a masonry surround with enough thermal mass to store and release the heat after the fire burns out.
You’ll get the most efficiency by burning seasoned hardwood
or manufactured pellets made from com pressed sawdust. Never
burn unseasoned “green” wood, railroad ties, pressure-treated
lumber or plastics in a woodstove.