Osburn STRATFORD II OB04007 Installation And Operation Manual page 22

Here are some suggestions for building fires suitable for different heating needs.
5.7.1 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" (76 mm) to 4" (102 mm) 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.
5.7.2 Low and Long Output Fires
For a fire that will last up to eight hours but will not produce intense heat, use soft wood and
place the logs compactly in the firebox. Before reducing the air intake, the load will have to burn
at full heat for long enough for charring the surface of the logs. The flame must be bright before
letting the fire burn by itself.
5.7.3 High Output Fires
When heating needs are high during cold weather, the fire should burn steadily and brightly. This
is the time to use larger pieces of hardwood. Place the biggest pieces at the back of the firebox
and place the rest of the pieces compactly. A densely built fire like this will produce the longest
combustion this fireplace is capable of. Special attention must be paid when building fires like
this since if the air intake is reduced too quickly, the fire could smoulder. The wood must be
flaming brightly before leaving the fire to burn.
5.7.4 Maximum Burn Cycle Times
The burn cycle time is the period between loading wood on a coal bed and the consumption of
that wood back to a coal bed of the same size. The flaming phase of the fire lasts for roughly
the first half of the burn cycle and the second half is the coal bed phase during which there is
little or no flame. The burning time expected from this fireplace, including both phases, will vary
depending on a number of things, such as:
− firebox size,
− the amount of wood loaded,
− the species of wood,
− the wood moisture content,
The table below gives an approximate maximum burn cycle times, based on firebox volume.
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Table 1 : Approximate Maximum Burn Cycle Time
FIREBOX VOLUME
<1.5 cubic feet
1.5 c.f. to 2.0 c.f
2.0 c.f. to 2.5 c.f.
2.5 c.f. to 3.0 c.f.
>3.0 c.f.
− the size of the space to be heated,
− the climate zone where the house is, and
− the time of the year.
MAXIMUM BURN CYCLE TIME
3 to 5 hours
5 to 6 hours
6 to 8 hours
8 to 9 hours
9 to 10 hours
Installation and Operation Manual - Stratford II