High Valley 2500, Owner'S Manual, Page: 24 / 28

24
A ̴ B W C
Before ligh ng the fi rst fi re in your new wood heater, please
read the following informa on outlining the basic elements
of clean wood combus on. Space is limited here, but much
has been wri en on the subject and is available elsewhere.
T C T :
Air, Fuel, and Heat (Ig-
ni on) are required to establish and support combus on
whether wood, coal, wood pellets, gas, oil, etc. is the fuel be-
ing burned. The correct propor on of air and fuel will vary,
but the three basic ingredients are essen ally the same.
I :
Igni on in a wood heater is straigh orward.
Typically it involves a match, paper, and kindling wood.
Enough heat must be generated and sustained to get the
cord wood burning (@ 350°C to 500°C**). For compari-
son matches are es mated to burn at 600°C to 800°C; a
standard butane lighter is somewhat ho er at @ 800°C to
1100°C, paper will ignite at @225°C to 250°C and dry so
wood kindling at @350°C. You light the paper with a match
to ignite the kindling and,
fi nally, the cord wood.
NOTE: There are any number of " fi restarters" on the mar-
ket. They light easily with a match and eliminate the need
for newspaper. Look for clean burning
fi restarters that are
approved for use with cataly c combustors. Never use
any fl ammable liquid (s) to start or "freshen" the fi re.
F :
The Model 2500 is designed and approved for use
with solid natural wood. Use of any other fuel may create
excessive emissions and will void the warranty.
The cord wood that you will burn depends to a large de-
gree on what species of trees are abundant where you live.
Transpor ng hardwood from its source to an area where
hardwood is scarce would be cost prohibi ve. If you live
where only so wood species are available, then that is
what you will likely use for fuel. In fact all cord wood, re-
gardless of species, has approximately the same poten al
BTU's* in each pound of wood. A pound of so wood has
the same poten al @ 8600 BTU's (kiln dry) per pound as
a pound of hardwood. "Hardwood" is denser than "so -
wood", varies in speci
fi c gravity, and is therefore heavier by
volume; and, of course, wood is sold by volume, not by the
pound. A cord of hardwood will take up the same space as
a cord of so wood but it will be heavier and contain more
poten al BTU's.
NOTE: The common unit for the sale or purchase of
fi rewood is the cord. One cord equals 128 cubic feet (4'
high x 4' wide x 8' long). Because cord wood is irregularly
shaped it would be impossible to achieve a solid 128 cu.
. block of wood. Wood is supposed to be "well stacked"
in a proper cord but that is a subjec ve measure. 85%
wood and 15% air space is commonly accepted as the
proper ra o but some sources cite 70% wood and 30%
air space. That represents signi
fi cant di ff erence of @ 109
cu. . to @ 90 cu. . of usable wood.
Along with density, the other major variable in wood fuel
is moisture content. Unseasoned or "Green" wood will
contain 50% water or more. Good "air-dried" cord wood is
about 20% moisture. At 20% moisture the available BTU's
will be @ 6200 to 7000 per pound not 8600. At 50% mois-
ture "green" wood will have only @ 4000 BTU's per pound
or less. It follows that cord wood needs to be well sea-
soned. It may take 9 months for so woods and up to 24
months for hard woods to air dry thoroughly.
C :
Clean, e ffi cient combus on in your wood
heater depends on burning well seasoned, good quality
fuel. Buying "seasoned" wood in the burning season is ex-
pensive and o en disappoin ng. The best advice is to get
"green" wood in early spring and air dry it yourself. If you
don't cut your own wood,
fi nd a reputable, reliable wood
seller. Well seasoned wood typically exhibits dark cut ends
with radial cracks, but spli ng a "dry" log and tes ng it with
a meter eliminates specula on. Home moisture meters
have become a
ff ordable and readily available. Follow the
instruc ons that come with the meter. Stack your wood o ff
the ground in a well ven lated area, preferably under cover
or with a tarp over the top of the stack. More informa on
on wood and wood species see Appendix - B on
Page 25 .
A :
The other leg of the combus on triangle is air. The
air needed to support combus on is drawn into the fi rebox
by the dra of your chimney. See Page 6 . Final air delivery
and metering required much research and engineering to
ensure clean combus on but, the good news is, you regu-
late the combus on air with one control. As long as your
chimney dra s well, air control is simpli
fi ed. It is against
federal regula ons to alter the air control se ngs or con-
trols in any way.
S C :
Put the three elements of the
Combus on Triangle together in your wood heater and you
will have started a
fi re. The chemical and physical processes
taking place in that fi re are complex, and scien fi c papers on
the subject are lengthy and detailed. Three major stages are
worth no ng and will help the operator understand how to
achieve the cleanest burning
fi re.
S O :
Kindling & Moisture Evapora on:
Kindling the fi re has been covered above under Igni on.
Provide enough heat to the wood for a long enough me
and it will begin to burn. Before the
fi re can reach full heat-
ing poten al moisture in the wood must be evaporated.
This is why dry fuel is so important. More than 1000 BTU
of poten al heat will be needed to drive o
ff each pound of
water. Un l the water present in the wood is boiled o ff the
fi re will be rela vely cool, heat from the coal bed will be
used up, and fl ue gas temperatures will be reduced. Burn-
ing green wood wastes a lot of energy.
S T :
Gas Vaporiza on & Igni on:
A er moisture is driven o ff , the temperature of the fi re
builds and various hydrocarbons and other elements begin
to vaporize. At temperatures of 500°F or more the Cataly c
Combustor will ac vate or "light-o
ff ." The Combustor is fu-
eled by the vola le gasses which will ignite at lower tem-
peratures in the presence of the catalyst. Temperatures in
the range of 1100°F to 1400°F are achieved and more heat
is released to heat the home.
S T :
Charcoal Burning:
A er fl ammable gasses have been burned o ff , only charcoal
remains. Charcoal burns cleanly at @ 1100°F in the pres-
ence of oxygen. Adjust the Air Control as needed to extend
the
fi re. If a con nuous fi re is desired, add fresh fuel while
the charcoal bed is s ll hot enough to kindle the new wood.
*
A Bri sh Thermal Unit (BTU) is a measure of the amount of energy (heat)
required to raise one pound of water by 1°F at sea level.
**The temperatures are given in Celsius and the temperature ranges are
approximate as the values vary from source to source.