Bosch Worcester Greenstyle Bewdley 8 Installation, Servicing And User Instructions Manual page 20

FACTORY BUILT CHIMNEY
When a metal prefabricated chimney is used, the manufacturer's
installation instructions must be followed. You must also purchase
(from the same manufacturer) and install the ceiling support
package or wall pass-through and "T" section package, firestops
20
51mm
(where needed), insulation shield, roof flashing, chimney cap, etc.
Maintain proper clearance to the structure as recommended by the
manufacturer. The chimney must be the required height above the
roof or other obstructions for safety and proper draught operation.
INSTALLATION
6720818040 B 04/2017