Metal Flue Box And Hearth; Precast Concrete Or Clay Flue Block System And Hearth - Valor 956 Installer And Owner Manual

INSTALLER GUIDE

4.10.2 Metal flue box and hearth.

The appliance can be installed to a fireplace
incorporating a metal flue box complying
with the constructional requirements of the
current edition of BS 715 and with a flue
conforming to BS EN 1856 part 1. The
dimensions of the flue box must conform to
those shown in figure 5.
The top surface of the metal flue box must
be covered with a 50mm layer of mineral
wool or equivalent insulation (See figure 5).
Important Note: Where the flue box has a
base sheet that is single wall (i.e. a single
metal sheet) the flue box must be mounted
on a non-combustible hearth. The hearth
material must be at least 12mm thick.
4.10.3 Precast concrete or clay flue
Figure 5. Metal flue box
block system and hearth.
The appliance can be installed to a
precast concrete or clay flue block
system conforming to BS1289 or BS
EN 1858 with dimensions as in
figure 6.
BS 1289 part 1 recommends there
should be an air space or insulation
between the flue blocks and the
plaster because heat transfer may
cause cracking on directly plastered
flues. However, generally this
appliance is suitable for installations
under all circumstances unless there is
a history of cracking problems.
Remember that faults such as
cracking may be caused by poorly
built and restrictive flues, e.g. mortar
extrusions, too many bends, flue
heights below three metres, restrictive
terminations etc.
The appliance is suitable for
installations conforming to older
versions of BS1289 as well as the
Figure 6. Pre-cast fireplace
©
GDC Group Ltd 2014
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