Duct Assembly; Fitting Flue And Air Ducts Onto An Elbow At The Appliance; Prepare The Roof; Fix The Flue System Assembly To The Appliance - Worcester 28Si Installation And Servicing Instructions

5.5 ASSEMBLY OF DUCTS
5.5.1 AIR DUCTS
Check the assembled length of the ducts. Drill two holes
through the pilot holes in the expanded end of the air duct
and fix the ducts together with the screws provided.
5.5.2 FLUE DUCTS
Fix the flue ducts together with screws provided ensuring
that any extension ducts have the seals fitted. Refer to Fig. 8.
The 750mm extension kits come complete with one flue
spacer. These must be fitted at about half distance, before
the ducts are finally assembled.
Assemble the flue duct into the air duct.
5.6 FITTING FLUE AND AIR DUCTS ONTO AN ELBOW AT
THE APPLIANCE
Fit the flue duct to the elbow ensuring that it is fully against
the stop.
Drill two holes through the duct into the elbow. Separate and
apply a smear of silicone sealant and fix with screws
provided. Fit the air duct over the elbow entry and repeat the
above process.

5.7 PREPARE THE ROOF

Remove sufficient roof tiles, or if a flat roof, cut a hole
approximately 175mm diameter for the flue terminal
assembly.
Fig. 13. Typical duct assembly.
Note: The flue terminal must
be connected a minimum of
55mm above any flue joint.
Where the flue ducts attach to the flue
terminal the air and flue duct length
should be equal. However the terminal
will assemble correctly if the flue tube is
longer or left uncut.
Fixing screws
Fixing screws
Seal
Appliance
10

5.8 FIX THE FLUE SYSTEM ASSEMBLY TO THE APPLIANCE

From inside the building, assemble the flue system starting
at the appliance. refer to Fig. 6, 8, 9 and 10.
Align the flue assembly or the first section of flue with the
flue adapter fitted on top of the appliance casing. Drill two
holes through the air duct and flue adapter and fix with the
screws provided.
If an elbow is fitted straight onto the boiler then locate the
elbow against the stop on the spigot on the boiler and fix
with the clamp. Refer to Fig. 8, 9 and 10.
Note: All ducts must be truly horizontal or vertical unless the
45° elbows are being used.
Check at each stage of the system assembly that each
section is properly aligned.
Each air and flue duct joint must be sealed and fixed. Each
air and flue duct connection to an elbow must be sealed with
silicone sealant and fixed with the screws provided.
Support any sections of the system until they are
permanetely fixed into place using suitable support brackets.
Terminal assemblly
height 1100mm
diameter 106mm
Smear silicone sealant
on this joint.
Seal
Ensure the ducts are
correctly located into
the socketed joints.
Vertical flue adaptor
88mm high.
Clamping ring
front