separator. If this is not used then a 672mm long fender, kerb, horizontal bar, or other
barrier, being fixed not less than 50mm above floor level and positioned 300mm in
front of the fixing plane of the fire will meet the requirement.
4.2.2
To a fireplace incorporating a metal flue box complying with the constructional
requirements of BS 715 and BS EN 1856 Part 1. The dimensions of the flue box must
conform to those shown in figure 2.
4.2.3
A precast concrete or clay flue block system conforming to BS EN 1806, BS EN
1858 or BS 1289 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 (NA 2.4) 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).
4.2.4
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.
4.3
Suitable flues and minimum flue sizes are as follows: -
It should be noted that, as with many appliances, sharp bends or horizontal runs in
metal flues at the top of the system can be a cause of problems in these types of
installation.
!
225mm x 225mm conventional brick flue.
!
175mm diameter lined brick or stone flue.
!
200mm diameter factory made insulated flue manufactured to the current edition
of BS EN 1856 or BS 4543.
!
175mm diameter flue pipe. See BS6461 Part 1 for suitable materials.
!
Single wall, twin wall or flexible flue liner with a minimum diameter of 125mm. The
materials to be used are stainless steel or aluminium as specified in
BS EN 1856 Part 1. The liner must be sealed to the surrounding area above the
fireplace opening and to the top of the chimney. An approved terminal must be fitted.
Page 10
INSTALLER GUIDE
©
Baxi Heating U.K. Limited 2007.
Figure 2. Metal flue box
Summary of Contents for 757
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