front of the fixing plane of the fire will
meet the requirement.
4.2.3
To a fireplace incorporating a
metal flue box complying with the
constructional requirements of the
current edition of BS715. The
dimensions of the flue box must
conform to those shown in figure 2.
4.2.4
A precast concrete or clay flue
block system conforming to BS1289
or BS EN 1806 with dimensions as
in figure 3 or using a 05654K1
spacer kit. (Installation Instructions
part number 3003095). The current
versions of BS1289 and BS EN
1806 recommend that 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 (See
figure 3).
4.2.5
If the fireplace opening is
greater than the acceptable
dimensions given in this guide, do
not use the back of a fire surround
or marble to reduce the opening.
This may cause cracking of the
surround back or marble.
Page 10
INSTALLER GUIDE
©
Baxi Heating U.K. Limited 2007.
Figure 3. Precast or clay flue block system
dimensions
Figure 2. Metal flue box
