Precast Concrete Or Clay Flue Block System And Hearth - Valor Fires 963 Installer And Owner Manual

INSTALLER GUIDE

4.10.3 Precast concrete or clay flue 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 8.
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 current edition. The flue blocks must have a minimum width (Depth as you
look at the flue block when installed) not less than 63mm and a cross-sectional area
not less than 13,000mm 2 . Older editions of BS1289 required a cross-sectional area
of 13,000mm 2 . The current revision of the standard requires 16,500mm 2 . This
appliance is suitable in both cases. The total depth of the opening measured from the
finished front of the fireplace (Including plaster, surround etc.) must be 115mm.
Figure 8. Pre-cast Fireplace
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Baxi Heating U.K. Limited 2010.