3.3
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 BS4543.
!
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 BS715. 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.
!
A properly constructed
precast concrete or clay flue
system conforming to BS1289
or BS EN 1806. This system is
only suitable if the conditions
stated in section 3.2.3 are met.
3.4
The flue must conform to BS 5440: Part 1 in design and installation.
The flue, measured from the bottom of the fireplace opening to the bottom of the
terminal, shall be not less than 3m in actual vertical height. When calculated in
accordance with BS 5440: Part 1 Annex A, the minimum
equivalent
height of the flue
shall be 2.0m of 125mm dia. flue pipe.
Page 10
INSTALLER GUIDE
©
Baxi Heating U.K. Limited 2006.
Figure 3. Precast or clay flue block system