1. The equation for combustion is time temperature and turbulence and the
proper air to fuel mixture.
- Time is required to allow thorough air and fueling mixture.
- Temperature is important since the rate of the chemical reactions which
are the essence of the combustion process, increase exponentially with
temperature. High temperature in the combustion zone, ensures
- Turbulence is an important factor because wood-derived fuel-gases and
air must mix to attain ignition and in order to sustain the combustion
process, the burning and already-burned gaseous materials must mix
with fresh fuel-gases and air.
- Air to fuel ratio is expressed as the mass air used to burn a unit mass of
fuel. Air to fuel ratio is important for accomplishing efficient combustion.
- Poor combustion causes smoky and inefficient heat transfer. Combustion
air control is the only method available for controlling the rate of
combustion in batch loaded fuel systems. Gaseous combustions cease
when combustion gas temperatures drop below approximately 950
2. Creosote is the condensation of unburned vapors from wood. Most
creosote is formed at startup,when wood is burned at a low heat-producing
rate without sufficient air, and when wet wood is burned. The Lil’ Powerhouse
is designed for small, dry wood so creosote build up is not an issue. In an
outdoor wood boiler, green or wet wood is burned.
If green or wet wood is burned, the flame temperature may be lowered to
where the gases are only partly burned. This will actually result in creosote-
forming conditions. The creosote will be a nuisance and a hazard if green
wood is burned for a long time. Choose the proper size wood burning
appliance. Do not install one so large that it is most often used at low heating
rates. The Lil’Powerhouse not only has you burning dry wood, but smaller dry
wood so you save energy.
3. Natural Draft is a relatively weak driving force (generally less than 0.1
inches water column).
4. Smaller fuel charges required with smaller fireboxes reduce emissions
rates when compared to larger fuel loads consumed at comparable burn
5. The efficiency of a grate less stove is always inferior to that of one with
a good grate.
- America currently burns over 40 million cords of wood annually for home
- Approximately three percent of the nation’s residential heating
requirements is now satisfied by wood. This represents about 1percent
of our national energy needs.
- About 87 percent of this is burned as the primary or secondary residential
heating source, and most of it comes from sources that do not compete
with pulpwood or lumber supplies.
If fuel is burned on a grate, air is forced through a bed of solid fuel
particles, and the necessary temperature is maintained by inter particle
radiation. Air-to-fuel ratios depend mainly on type of fuel.
- Estimate Woods Fuel Value
The Heating value of softwoods is generally higher than that of
hardwoods. Value of hardwoods is about 8600 BTU’s per dry pound, and
softwoods is about 9,000 per dry pound.
For safe and effective burning, it is suggested that fuel wood be dried for
three months to two years. This is however for longer and larger
diameter pieces. For wood that had been split into stove lengths, the
drying time is much shorter.