Air Intake Control; Fire Types - Osburn CW2100 Owner's Manual

3.7

Air Intake Control

Once the firewood, firebox and chimney are hot, air intake can be reduced to achieve a steady
burn.
As the air intake is reduced, the burn rate decreases.
This has the effect of distributing the thermal energy of
the fuel over a longer period of time. In addition, the
flow rate of exhaust through the appliance and chimney
slows down, which increases the duration of the energy
transfer of the exhaust gases. As the air intake is
reduced, the flame slows down.
If the flames diminish to the point of disappearing, the
air intake has been reduced too early in the combustion
cycle or the wood used is too wet. If the wood is dry
and the air control is used properly, the flames should
decrease, but remain bright and stable.
On the other hand, too much air can make the fire
uncontrollable, creating very high temperatures in
the unit as well as in the chimney and seriously
damaging them. A reddish glow on the unit and on the
chimney components indicates overheating. Excessive
temperatures can cause a chimney fire.
3.8

Fire Types

Using the air intake control is not the only way to match the insert heat output to the desired
temperature in the house. A house will need far less heating in October than in January to
maintain a comfortable temperature. Filling the firebox full in fall weather will overheat the space.
Otherwise, the combustion rate will have to be reduced to a minimum and the fire will be smoky
and inefficient. Here are some suggestions for building fires suitable for different heating needs.
The method used to certify your appliance according to EPA Standards is presented in the EPA
Loading Section of the Wood Insert Installation and Operation Manual of your appliance.
3.8.1 Flash Fire
To build a small fire that will produce a low heat output, use small pieces of firewood and load
them crisscross in the firebox.
The pieces should only be 3 " to 4 " in diameter. After raking the coals, lay two pieces parallel to
each other diagonally in the firebox and lay two more across them in the other direction. Open
the air control fully and only reduce the air after the wood is fully flaming.
This kind of fire is good for mild weather and should provide enough heat for up to four hours.
Small fires like this are a good time to use softer wood species and avoid overheating the house.
Wood Inserts – Owner's Manual
The images shown are for guidance only
and may differ from your product, but the
operation remains the same. See the EPA
Loading Section of the Insert Installation and
Operation Manual for a specific overview of
the air control of your appliance.
Figure 1 : Air Intake Control
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