Isokern FIRE-LITE series, Owner'S Manual

Page: 35 / 59

35
DM 54 Chimney System: Offset Block (cont.)
Calculating Offsets:
To calculate the distance of Isokern offset chimney travel
in a straight line to the right, left or to the rear of the firebox/smoke
dome assembly, proceed as follows:
Refer to Figure 59: temporarily dry set a DM 54 outer casing
block in its proper location on top of the completed firebox/smoke
dome assembly as though starting a straight chimney.
If the offset sequence is to move to the left then, starting
from the right side of the temporary DM 54 outer casing measure
left ward to the far face of the overhead obstruction that needs to be
bypassed by the vertical chimney run.
For accurate measuring drop a plumb line down from the far
face of overhead obstruction to the level of the top of the smoke dome
assembly. Measure from the far side of the temporary DM 54 outer
casing to the plumb line.
This measurement, taken in inches and divided by three
(three inches of horizontal travel per offset block) gives the total num -
ber of offset blocks needed to accomplish the required travel distance.
To calculate the height that the offset block sequence will
require, take the total number of offset blocks needed to accomplish
the travel distance (described above) multiplied by 6”. This number is
the height (inches) that the offset sequence will require.
When establishing the “far face” of the overhead
obstruction, be sure that the DM 54 chimney blocks can run straight
to chimney termination without further overhead obstruction since a
second offset sequence is not allowed. (Figure 60)
Be sure that there is sufficient space beyond the “far face” of
the overhead obstruction to accept the DM 54 chimney’s outer casing
dimension of 21 1/2”.
Support all offset sequences down to bearing as previously
discussed on page 34.
Notes:
Always support the last offset block in a sequence for full
support of the DM 54 chimney where it returns to vertical.
Support columns often carry the majority of the total load of
the vertical chimney that is set onto the last offset block.
The total chimney weight above the last offset block
will be the total weight of the vertical chimney plus any additional al -
lowable loads such as the Isokern brickledge, its related brick or stone
veneers, and any crown caps, clay pots or other masonry chimney
terminations.
Be sure the foundation under all support columns is made of
concrete or steel and designed to support the loads applied to it.
Check with local codes and a structural engineer to confirm
loading and foundation requirements.
Chimney runs are limited to one offset sequence per chim-
ney system.
Maximum horizontal distance of offset is six feet (6’) and
represents twenty-four offset blocks in sequence.
By code the maximum angle of offset for chimney system is
30° off of vertical.
FIGURE 59
FIGURE 60