Osburn 3500-I, Installation And Operation Manual

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Page 22 Installation and Operation Manual - Osburn 3500-I
ENGLISH
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 insert 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 insert, 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 size of the space to be heated,
− the climate zone where the house is, and
− the time of the year.
The table below gives an approximate maximum burn cycle times, based on firebox volume.
Table 1 : Approximate Maximum Burn Cycle Time
FIREBOX VOLUME MAXIMUM BURN CYCLE
TIME
<1.5 cubic feet 3 to 5 hours
1.5 c.f. to 2.0 c.f 5 to 6 hours
2.0 c.f. to 2.5 c.f. 6 to 8 hours
2.5 c.f. to 3.0 c.f. 8 to 9 hours
>3.0 c.f. 9 to 10 hours
A longer burning time is not necessarily an indication of efficient insert operation. It is preferable
to build a smaller fire that will provide three or four hours of heating than to fully load the firebox
for a much longer burn. Shorter burn cycles make it easier to match the heat output of the insert
to the heat demand of the space.
5.7.5 Logs Orientation
In a relatively square firebox, the wood can be loaded north-south (ends of the logs visible) or
east-west (sides of the logs visible).
North-south loads allow more wood to be loaded at the same time. On the other hand, they
break into smaller pieces faster. North-south loading is good for high output, long lasting fires
for cold weather.
East-west loads allow a limited amount of wood since too many logs could cause them to fall
on the glass. East-west loads, placed in a compact way, take a long time before breaking down.
They are excellent for low-intensity, long-lasting fires in relatively mild weather.