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5
.3 BRICK, STONE ETC. BUILDING. CONVECTION BOX
RECESSED INTO WALL (Figure 8)
5.3.1
This installation has the convection box
recessed into the wall of the building. The front
flanges of the convection box and the appliance
metal decorative surround will abut the front
surface of the wall.
5.3.2.
The non-combustible hearth must project
at least 345mm in front of the convection box
front flanges and be at least 620mm wide (Figure
8).
5.3.3
The recess in the inner wall for the
convection box should be to the size shown in
figure 1. The bottom of this recess should be at the
same level as the top surface of the hearth.
5.3.4
A lintel may be required above the recess for
the convection box. If in doubt, seek expert
building advice before commencing to cut the
recess.
Whenever a lintel is required to support the recess
in the inner leaf of a brick/blockwork building,
follow the method outlined below. See figures 8a & 8b.
1. The lintel should be either steel (Catnic) or reinforced
precast concrete. It should be 750mm long x 75mm deep x
inner leaf thickness.
2. The opening should be, as near as possible, centrally below a
joint in the inner leaf block.
3. Cut out the opening for the lintel.
Where cutting through masonry, drill pilot holes and then
cut out the slot using a mechanical cutter. This will
minimise damage to the surrounding structure.
4. Insert the lintel. Bed the lintel on mortar. Don’t dry bed.
Slate pin to ensure the lintel and structure above is secure
and safe
5. Make the opening below the lintel by removing the masonry
and clearing debris. If the cavity has loose fill (e.g. granular)
insulation material, pack the edges of the opening with
Rockwool as you proceed to hold back the insulating
material.
5.3.5
Note that more clearance between the recess and the
convection box is required at the left side than at the right side
(Figure 1c). Bear this in mind when centring the flue box hole.
5.3.6
The rectangular hole through the wall to cater for the flue
box should be to the size shown in Figure 8. The bottom of the
hole should be at the same level as the top surface of the hearth. In
almost every case, it will not be necessary to support this hole with
a lintel. If, however the wall is of poor construction seek expert
building advice before commencing to cut the hole.
5.3.7
The wall cavity must not be bridged other than by the flue box. The
convection box must not project into the cavity between the inner and outer
walls by more than 10mm.
Figure 8b
Figure 8a
Figure 8
