FMI VENT FREE UNIVERSAL MASONRY FIREBOX MM39/44/49VF - Manual (Page 15)

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Figure 21
Combustion Air Access
Right or Left (Right shown).
Apply
mortar
Apply mortar
Side Wall
Rear Wall
Side Wall
When you have arranged all the components into place 7)
and you are working on the top rear firebox, check that
your work is level. If you need to, you can make some
adjustments in the top surface of the box assembly
simply by using shims. Once you are satisfied with the
degree of levelness, you can address any gap that may
have occurred with an appropriate amount of mortar.
Although you are cautioned to use mortar sparingly
because it does have such holding power, you should
look over the firebox assembly at the end and fill any
gaps with mortar especially at joint connections.
Adjustments must be made to ensure the fireplace is level
and square while the mortar is still wet.
After fourth row of walls are in place, add 36” rebar to all 8)
cells as shown in Figure 22. The rebar should enter the
holes in the Hearth and lie adjacent to the 12” rebar secured
in subfloor. Then fill cells with approx. 2 cu.ft. Ready-Mix
Concrete.
Figure 22
12 inch
rebar
Add rebar after
fourth row
Temporarily place Lintel between side walls, making sure 9)
it is flush to the front and snug at the inside. Check for
alignment. Remove Lintel and apply mortar on surfaces to
be mated. Install Lintel.
Install Lower Rear Dome flush to the rear walls as shown in 10)
Figure 23.
Figure 23
Lintel
Lower
Rear Dome
11) Place Lower Side Domes between Lintel and Lower
Rear Dome to verify fit. The face with the rating plate faces
the inside of the firebox as shown in Figure 24. Remove
and prepare mating surfaces with mortar. Assemble Lower
Dome Sides and check that all four top surfaces are level
with each other. Shim if necessary.
Figure 24 Lower Dome Sides
(Rating Plate faces inside)
12) Now install the Smoke Dome Tops. Align outer edges with
Lower Dome Sides. Check for flatness and squareness.
Figure 25