INSTALLER’S GUIDE
Page 6
Fig. 3 Precast or clay flue block system
Requirements for use with kit 617K
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 distance from the back
face of the flue starter
blocks to the extreme front
face of the fireplace
including all surfacings
must be no less than the
distance shown in figure 3.
The distance from the front
face of the flueway
opening in the lintel block
(or equivalent) to the
extreme front face of the
fireplace including all
surfacings must be no more
than the distance shown in
figure 3. If this maximum
is exceeded poor clearance
of combustion products could result.
The flue starter blocks should not be modified.
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.
2.3.2
Into a fireplace that has a fireback of nominal size 400mm or 450mm and
conforming to BS1251. The distance from the front face of the flueway opening in the
lintel (or equivalent) to the extreme front face of the fireplace including all surfacings
must be no more than the distance shown in figure 4. If this maximum is exceeded poor
clearance of combustion products could result.
