MAGNUM MASONRY MANUAL – MAY 1999 PAGE - 8 -
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The ceiling height and the height of the flue extension determine the heat chamber height. The top
vent must remain a minimum of 17” below the ceiling level.
Note:
If a wooden header is used above
the top slab, 12” minimum of clearance is necessary. This open area also should be filled with loosely
filled fiberglass with the paper backing removed.
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The Magnum (be careful of your back) should now be placed within the cavity allowing 4” of
clearance on the back and sides. From the faceplate of the fireplace, allow 4” back to the leading edge
of the block heat chamber. Remember that the face brick must not directly touch the steel at this
point. By using the adjustable legs, level and plumb the unit across the face.
Note:
Remove glass
doors so they are not damaged in steps to follow.
Note:
the (4) 3/8 bolts for the legs are in the
hardware bus provided with the unit.
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Assemble outside air hook-up using elbows where necessary. It is recommended to seek the closest
access to the outside as possible, using no more than three elbows and running not more than 10 feet.
Combustion air may be brought through a crawl space or below the slab, but must have a direct
connection to the outside. Do not terminate in an attic or garage or run vertically more than 6’.
Always provide a rodent screen at the end of the termination. The dust must terminate below the level
where it enters the firebox to minimize a reversed flow condition.
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Position the flue extension on the fireplace unit.
Note:
Offset flue extensions (8” & 16” of offset) are
available to connect a chimney not centered with the unit. See your Magnum dealer for details. (SEE
FIGURE #__________)
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Position properly sized slab support over the flue extension so that the holes line up and that the plate
overlaps the Hadite block 2”. The slab support plates available from your Magnum reseller are
constructed of 10-gauge steel.
Note:
This concrete slab form can be constructed out of other
materials, including plywood. Proper support from below and caution to remove all combustibles
from the heat chamber laying up face brick are a must.
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Wrap the 6” insulation with foil facing out around the top of the flue extension. Make sure that the
insulation is 1” above flue extension so that concrete will not fall into the flue extension. It is best to
make an 8” x 12” x 1” thick form to put on top of the flue extension when pouring the concrete slab.
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Provided that you have positioned your re-bar properly (SEE FIGURE _______), you are ready to
pour the 5” slab. It is best to mix your concrete thick so you can work with it faster.
Note:
The
insulation acts as an expansion contracted joint between the flue extension stainless steel adapter and
concrete.
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When the concrete has set up so that you can work with it, take the 8” x 12” x 1” thick form off of the
flue extension. This gives you the 1” expansion room between the flue extension and the stainless
steel adapter. Slide the adapter down into the flue extension until the adapter rests on the concrete
slab. Then tap the adapter slightly into the concrete for a positive seal.
Allow the concrete to cure
for 24 hours before continuing with the installation.
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The stainless steel adapter (part # SSA-10) has been designed to act as a slip joint between the
chimney that cannot move and the steel assembly of the fireplace that can move up to a full 1” under
extreme firings. Make sure to radius the corners so that the creosote will run to the inside of the stack.
(SEE FIGURE _______)
